webms continue playing after they are minimized

[Former user]

Clicking on a webm expands them to full resolution and autoplays with sound correctly.

However, clicking on them and minimizing them back to their thumbnail, they appear to continue playing in the background as well as the sound continuing to play on loop. There is no way to cancel the playback of these background webms besides refreshing the thread.

[Ponychan]

Duplicate of #26.