Simple and does what it says. Worked for my need. Thanks!

Very useful and unique extension. Thanks a lot.

Very useful, almost perfect, especially on sites like Reddit. I would really love the option to show the channel name in the tooltip.

A very nice addition!

I found a bug.
On YouTube open any account, move the cursor over the clips - everything works fine.
But!
If - on the sidebar YouTube - open any account from 'subscriptions', then the notifications will appear from the preceding account! Helps only - to manually refresh the page.

And one more question: is it possible to show in addition to the length of the videos also its maximum resolution? It is not easy - to find among similar video that you can see with maximum quality.

Simply works as stated. I would love the inclusion of the "date created" field in the tooltip, a must-have as a reddit moderator
Edit: And the update works perfectly for the creation-date, thank you so much!

Tested on http and https links. Works quickly, with tooltip appearing after a short, appropriate delay. I'm glad to no longer have to click links just to see what the video is about. Thanks!