## Issue
6068 Fix "Cumulative Layout Shift" for Core Web Vitals
In Posts, the Comments section appears first while we fetch the MD file. When the MD is fetched, Comments get pushed to the bottom (or shifted up for short posts), hence the red CLS scores.
## Approach
There are too many layers between `<FilePage>` and `<DocumentViewer>` to pass the `loading` state around to hide the Comments section, so just make Comments fade in after a 2s delay.
## Changes
- Posts: Add 2s fade-in delay to Comments.
- Posts: remove the gray placeholder. This improves the score a bit more, and reduces flicker as well. There's already a spinner from `FileRenderInline` to tell the user to be patient.
- Posts: add a minimum 30vh height so that short posts don't get collapsed too much, causing the `FileDetails` and Comments to shift. Small shifts are fine as long as CLS is below 0.1.
## Issue
The loading circle wasn't showing up, causing confusion.
Splitting CSS doesn't seem trivial as there seems to be a huge dependency on the load order. Pretty much similar to what this person is facing https://lihautan.com/css-code-splitting/#the-problem
## Change
This reverts videojs-specific changes from 4d638bcf.
- The `rateChange` event now logs the updated speed,
not just the time at which it occurred.
- The `scrub` now (more) accurately logs the position
it came from before the destination.
- The recsys events get consolidated for logical consistency.
## Issue
When opening a video directly in Chrome Incognito, the video should autoplay (since that's the default Lbry setting), but it doesn't due to browser policy
https://developers.google.com/web/updates/2017/09/autoplay-policy-changes
## Changes
- We don't want to forcefully mute the video when `autoplay=true`; we just want to do it when the browser policy is applied.
- Fortunately, there is already an existing code-block for us to check that.
## Test cases
- [x] "Autoplay=Off" should not be affected.
- [x] After manually unmuting, the next autoplayed video should not be muted (this is "user interacted" opening, so the policy allows autoplay)
- [x] If manually muting, the next autoplayed video should retain user's last setting.
## Known issues
- I've seen `error` occasionally being undefined in the `catch` block. In those cases, the solution doesn't work. We could remove `if (player.autoplay() && !player.muted())` and simply just try muting it, but for now it's better to ensure `NotAllowedError` is due to unmuted first before applying the fix.
- This doesn't work for Firefox as there is an explicit "Allow Autoplay" button in the address bar that user needs to click themselves. Applies to all sites.
## Issue
One of the items in 5865 Video shortcut issues
This one is not really an issue, but it would be nice to match what the arrow keys are doing. Also, in slower regions, seeking 10s will almost always end up buffering.
## Changes
- Restore original code for how Volume and Mute is restored.
- Playback rate will be only change that gets "re-restored" in "loadedmetadata".
## Issue
5513: Video-setting persistence broken
## Notes
- Per videojs recommendation, the setting-restoration should be done after the video has been loaded, so the action was moved to `loadedmetadata`. This fixed the volume slider problem, and should have fixed the playbackRate too.
- For playbackRate, there is another special case where it gets reset to 1 (refer to comments in code).
## Issue
Partially closes 3041: Display/hint what keyboard shortcuts are available in videos
(minus the "all shortcuts" overlay -- saving that for another day)
