Keyboard shortcuts are not reliable upon first interaction

[tangodev]

When trying to use the well-known shortcuts for playback space and full-screen f this fails, but only for the first two times for a fresh viewer.

Bug reproduction

1. Paste a link to a DTube video on Discord
2. Open the link in a Private Window to simulate "first time user interaction"[1]
3. Try pressing space -- the screen will scroll down, playback will not start
4. Try pressing f -- no reaction
5. Click in the middle[2] of the player, playback starts
6. Try pressing space -- no reaction
7. Try pressing f -- no reaction
8. Click once again in the middle of the player -- playback pauses
9. Try pressing f -- playback starts again in full-screen
10. Try pressing space -- the video pauses

[1] When not using Private Mode, the video autoplays.
[2] I tried also to click strictly on the widgets (red play button etc.) and there was no difference.

Tested on Linux version of Brave 1.21.77 Chromium: 89.0.4389.90 (Official Build) (64-bit).