Firstly, captions were already very difficult to access with the mobile user interface, having to do multiple things to try and break the page to be able to turn them on. Now, even on PC when trying to turn captions on for a video with a long list of them, like a TV show or documentary, the list gets completely cut off.
For example, a video will have 14 options in the captions menu, however only the first 9 will show. It can be fixed by zooming out the page, however once again this is not possible for many mobile browsers, and even some browsers do not support zooming functions.
I might suggest adding a scrolling function to the captions list, or somehow changing the UI.
Thanks for your feedback. This has now been fixed!