diff --git a/av/container/core.pyi b/av/container/core.pyi
index 5f25e7030..1bbd82b26 100644
--- a/av/container/core.pyi
+++ b/av/container/core.pyi
@@ -3,7 +3,18 @@ from enum import Flag, IntEnum
 from fractions import Fraction
 from pathlib import Path
 from types import TracebackType
-from typing import Any, ClassVar, Literal, Self, TypedDict, cast, overload
+from typing import (
+    Any,
+    ClassVar,
+    Literal,
+    Self,
+    TypedDict,
+    cast,
+    overload,
+    type_check_only,
+)
+
+from typing_extensions import disjoint_base
 
 from av.codec.hwaccel import HWAccel
 from av.format import ContainerFormat
@@ -13,7 +24,7 @@ from .input import InputContainer
 from .output import OutputContainer
 from .streams import StreamContainer
 
-Real = int | float | Fraction | AVRational
+type _Real = int | float | Fraction | AVRational
 
 class Flags(Flag):
     gen_pts = cast(ClassVar[Flags], ...)
@@ -69,6 +80,7 @@ class AudioCodec(IntEnum):
     pcm_u8 = cast(int, ...)
     pcm_vidc = cast(int, ...)
 
+@type_check_only
 class Chapter(TypedDict):
     id: int
     start: int
@@ -76,6 +88,7 @@ class Chapter(TypedDict):
     time_base: AVRational
     metadata: dict[str, str]
 
+@disjoint_base
 class Container:
     name: str
     file: Any
@@ -87,8 +100,8 @@ class Container:
     container_options: dict[str, str]
     streams: StreamContainer
     metadata: dict[str, str]
-    open_timeout: Real | None
-    read_timeout: Real | None
+    open_timeout: _Real | None
+    read_timeout: _Real | None
     flags: int
     video_codec_id: int
     def dumps_format(self) -> str: ...
@@ -113,7 +126,7 @@ def open(
     options: dict[str, str] | None = None,
     container_options: dict[str, str] | None = None,
     buffer_size: int = 32768,
-    timeout: Real | None | tuple[Real | None, Real | None] = None,
+    timeout: _Real | None | tuple[_Real | None, _Real | None] = None,
     io_open: Callable[..., Any] | None = None,
     hwaccel: HWAccel | None = None,
 ) -> InputContainer: ...
@@ -125,7 +138,7 @@ def open(
     options: dict[str, str] | None = None,
     container_options: dict[str, str] | None = None,
     buffer_size: int = 32768,
-    timeout: Real | None | tuple[Real | None, Real | None] = None,
+    timeout: _Real | None | tuple[_Real | None, _Real | None] = None,
     io_open: Callable[..., Any] | None = None,
     hwaccel: HWAccel | None = None,
 ) -> InputContainer: ...
@@ -137,7 +150,7 @@ def open(
     options: dict[str, str] | None = None,
     container_options: dict[str, str] | None = None,
     buffer_size: int = 32768,
-    timeout: Real | None | tuple[Real | None, Real | None] = None,
+    timeout: _Real | None | tuple[_Real | None, _Real | None] = None,
     io_open: Callable[..., Any] | None = None,
     hwaccel: HWAccel | None = None,
 ) -> OutputContainer: ...
@@ -149,7 +162,7 @@ def open(
     options: dict[str, str] | None = None,
     container_options: dict[str, str] | None = None,
     buffer_size: int = 32768,
-    timeout: Real | None | tuple[Real | None, Real | None] = None,
+    timeout: _Real | None | tuple[_Real | None, _Real | None] = None,
     io_open: Callable[..., Any] | None = None,
     hwaccel: HWAccel | None = None,
 ) -> InputContainer | OutputContainer: ...
diff --git a/av/container/input.pyi b/av/container/input.pyi
index 819defd1b..449b56f10 100644
--- a/av/container/input.pyi
+++ b/av/container/input.pyi
@@ -1,5 +1,5 @@
 from collections.abc import Iterator
-from typing import Any, overload
+from typing import Any, final, overload
 
 from av.audio.frame import AudioFrame
 from av.audio.stream import AudioStream
@@ -12,6 +12,7 @@ from av.video.stream import VideoStream
 
 from .core import Container
 
+@final
 class InputContainer(Container):
     start_time: int
     start_time_realtime: int | None
diff --git a/av/container/output.pyi b/av/container/output.pyi
index 5487fdf77..e74cd6f65 100644
--- a/av/container/output.pyi
+++ b/av/container/output.pyi
@@ -1,6 +1,6 @@
 from collections.abc import Sequence
 from fractions import Fraction
-from typing import TypeVar, overload
+from typing import final, overload
 
 from av.audio import _AudioCodecName
 from av.audio.stream import AudioStream
@@ -15,8 +15,7 @@ from av.video.stream import VideoStream
 
 from .core import Container
 
-_StreamT = TypeVar("_StreamT", bound=Stream)
-
+@final
 class OutputContainer(Container):
     @overload
     def add_stream(
@@ -58,9 +57,9 @@ class OutputContainer(Container):
         rate: AVRational | Fraction | int | None = None,
         **kwargs,
     ) -> Stream: ...
-    def add_stream_from_template(
-        self, template: _StreamT, opaque: bool | None = None, **kwargs
-    ) -> _StreamT: ...
+    def add_stream_from_template[StreamT: Stream](
+        self, template: StreamT, opaque: bool | None = None, **kwargs
+    ) -> StreamT: ...
     def add_attachment(
         self, name: str, mimetype: str, data: bytes
     ) -> AttachmentStream: ...
diff --git a/av/container/streams.pyi b/av/container/streams.pyi
index bdab1ea54..f401a1cf3 100644
--- a/av/container/streams.pyi
+++ b/av/container/streams.pyi
@@ -1,11 +1,12 @@
 from collections.abc import Iterator
-from typing import Literal, overload
+from typing import Literal, final, overload
 
 from av.audio.stream import AudioStream
 from av.stream import AttachmentStream, DataStream, Stream
 from av.subtitles.stream import SubtitleStream
 from av.video.stream import VideoStream
 
+@final
 class StreamContainer:
     video: tuple[VideoStream, ...]
     audio: tuple[AudioStream, ...]
@@ -17,11 +18,9 @@ class StreamContainer:
     def __len__(self) -> int: ...
     def __iter__(self) -> Iterator[Stream]: ...
     @overload
-    def __getitem__(self, index: int) -> Stream: ...
+    def __getitem__(self, index: int, /) -> Stream: ...
     @overload
-    def __getitem__(self, index: slice) -> list[Stream]: ...
-    @overload
-    def __getitem__(self, index: int | slice) -> Stream | list[Stream]: ...
+    def __getitem__(self, index: slice, /) -> list[Stream]: ...
     def get(
         self,
         *args: int | Stream | dict[str, int | tuple[int, ...]],