seek on clicking timestamp links in comments

[yausername]

• I carefully read the contribution guidelines and agree to them.

Fixes #1968 (review)

There are some problems with the popup player:

1. start a video in popup mode by clicking on a timestep-link in a video description or comment
2. Notice the video repeating the first miliseconds again and again until some more of the video stream is buffered.
3. Let the video play for some seconds
4. Pause the video. Notice the current playback position is reset back to the point from where we started in 1.

In some cases this problem is even bigger.

1. start a video in popup mode by clicking on a timestep-link in a video description or comment
2. start another video in popup mode by clicking on a timestep-link in a video description or comment
3. let the first video finish or skip it (to skip it, click on the popup notification and then press the control to get to the next video
4. You'll be in an endless loop of the first frames. The only way the interrupt the loop is pressing the pause button. after pressing play again, the video is played properly.

[TobiGr]

Thanks! Looks good and works way better now 👍

[TobiGr]

Thanks, I forgot to merge 🤦‍♂️