Interactive Video in Course Presentation not visible / supported

Hello,

I have installed a Moodle and created a course presentation with 4 slides. On each slide there is an interactive video element with a video of a size of 200 MB. When viewing this page where the course presentation is embedded in my browser (Firefox 95.0 + Chrome 96.0.4664.93) I face no problems, the video is shown like expected and works. Same with my iPhone 8 and an older Android Phone (don't know the version).

But when viewing this with a Android tablet (Nexus 7, Android Version 6.0.1) I can't view any of the videos. The first problem occurs when calling the website in the browser and this is not a h5p problem but the https is viewed as not secure.

The second problem is when going on to the "not secure" page with the embedded videos I get the message "This video format is not supported". I am using WLAN, not LAN but never faced this problem on my laptop. I called the website with the video once in another WLAN and I could watch the videos sometimes, but faced sometimes the named error message. The videos are all in .mp4 format.

And the third problem I faced is that the whole course presentation is embedded in another website via an iFrame. When viewing this in browser, no problems at all, when viewing this on the named tablet I get a grey window instead of the video with the message, that the video under the given URL isn't available right now or has moved to another URL. But I can see and watch the video on my laptop.

URL to the video embedded in a website: https://www.deutsche-depressionshilfe.de/unsere-angebote/fuer-firmen-und...

URL to the video created in Moodle: https://www.esor-fortbildung.de/mod/hvp/view.php?id=1

I hope you can help me with this issue :/

Edit: I attached an image for the third problem.