The name "Quit watch later" is hard to understand for users that don't
already know about the quit-watch-later command.
For what it's worth, this does also have some downsides:
1. It makes the context menu even wider, since "Quit watch later" was
already the longest option.
2. The meaning of the "Open > Watch later" option may now be slightly
less obvious to users. But this option does not work by default
anyway, so the user will need to read the manual either way before
using this option.
But these are fairly minor issues.