VideoPress: add option to select video thumbnail

[jeherve]

Update: This issue remains but the workaround below is no longer valid due to the refactor of VideoPress. Leaving the text for historical reference.

Original Post:
At the moment, if you want to change the video thumbnail of a video you just uploaded to VideoPress, you have to follow these steps:

1. Log in to WordPress.com
2. Go to the WordPress.com site where you've purchased the VideoPress upgrade
3. Go to Media > Library in your dashboard
4. Select a video you want to edit
5. Change the thumbnail.

It'd be nice if this option were available under Media > VideoPress in dashboards where the VideoPress module is active.

Suggested here:

• https://twitter.com/kbfl/status/448500159194726400

[kriskarkoski]

On AT sites it is not possible to change the thumbnail as the WordPress.com library cannot be accessed

[jeherve]

@kriskarkoski Correct. It's not possible on any other Jetpack site either since VideoPress videos are now linked to the Jetpack site, and not to a WordPress.com site using a VideoPress upgrade.

Luckily the work we've done in #6631 will soon allow one to change a video poster directly from Calypso, once this PR will be complete and merged:
Automattic/wp-calypso#11653

[seejacobscott]

requested here: 3265255-t

[aheckler]

634025-zen

[danjjohnson]

Looks like this is now possible via #6631 but I've just found that it doesn't seem to show the selected thumbnail in Safari. Or rather it shows it briefly, then reverts back to the first frame of the video.

Steps to reproduce:

1. Upload a video to a page/post and select a frame to use as the thumbnail, via https://wordpress.com/media/
2. View the page/post in Chrome and you'll see the selected frame.
3. View the page/post in Safari and you'll see the selected frame for a second, then the first frame.

cc: @donnapep as you worked on the PRs for this I believe.

Reported in 701879-zen

[aheckler]

cc @dbtlr here ^^^ since that sounds a lot like the issue you just dug into for me.

[dbtlr]

@danjjohnson This is due to the removal of autoplay from Safari for ads. We've removed most of the VideoPress interface from Safari at the moment while I investigate how we can be compliant with this change in Safari and elsewhere. You can find more in 43-gh-guardians