when fullscreen video in aside tag footnote apear on top and cover video

Hi, Im creating an e-book and I added into this book video. This video is placed into aside tag. So user can view this video after clicking on link which will open this aside footnote. But problem appeared when user want to use full screen on this video. Footnote jump to front of view and cover video. I tried edit CSS but everything was unsuccessful.

Here is screenshot

Here you can see this foot note which cover video

Thank you for answers.