When using timestamps and taking notes from Youtube videos it would be helpful if there was an offset to the timestamp taken.
This could be implemented as a configurable parameter (offset) in settings (e.g. timestamp is always set at x seconds before the time the Shift+Cmd/Ctrl+Y key was pressed and/or it could be implemented as +/- buttons next to the timestamps so that it can be configured on the fly, like this:
Note: I am speaking of Youtube here, but the functionality would be just as useful on Vimeo embeds etc.