Comment 2 for bug 1616896

Hm, this is an interesting UX question. Technically, "this is a feature, not a bug." Fullscreen windows, whether a video or otherwise, are opened onto a new workspace. Window Switching (Alt+Tab) in elementary OS is designed to be per-workspace. Since a fullscreen window is on its own workspace, there are no windows to switch between, so Alt+Tab doesn't work.

If you manually move another window onto the workspace with the fullscreen video, you'll see Alt+Tab does work.

There are a few options here:
1. Consider this working-as-designed,
2. Change Alt+Tab to cycle between all windows, not just the current workspace,
3. Make initiating Alt+Tab un-fullscreen any fullscreened windows on the current workspace.

Each of these has some problems.
1. This obviously feels broken to OP, and I can see the line of thought,
2. Alt+Tab being bound to the current workspace is by design, and I don't know that changing that is a net positive,
3. This could cause some weirdness where we end up changing workspaces in the middle of an Alt+Tab animation, and might also be confusing.

Assigning to UX team to discuss.