Button for playback speed menu needs better accessible label.
Currently, when using a screenreader, the label of the playback speed menu is the current rate. For instance, "1.0x".
Accessible label should be: “[X] playback speed”, with X being the currently set rate. For instance, "1.0x Playback Speed".
The button is styled as a little clock overlaid with the current rate. Updating the label will help convey the information presented by the clock.
The button is semantically and interactive button and so the screenreader adds that information in. If we update the label, what will actually be read out is something like "1.0x Playback Speed, double tab to activate" (language pending different screenreaders.) So we don't need to worry about including anything like "button" in the accessible label.

Mark's investigations have found an accessibility limitation where we cannot overwrite text with an accessible label.

"Unfortunately, it seems like this one just isn't possible. We are definitely setting the "content description" (the bit that's read out by the screen reader) to the correct "one and a half times playback speed" string, but it seems that Android ignores those for text views and just uses the content of the text view instead. This means that it'll just say 1.0x → "one point oh ecks" because that's what the onscreen text says."

We are not able to addess this issue with the existing api and to add that enhancement will need to rethink design.