Multivideo page - videos freeze

Please forgive if this is a repeat.  I am new and I don't see my other post.  I don't know if I'm supposed to see my own posts in the forum.  

I have a multivideo page with about 60 H5P videos (1-5 minutes each).  It's a summary search page of all the bookmarks on my site (educational). Elsewhere, it's one H5P video per page.  This is a "site index" of all the bookmarks in one place. 

These videos all have bookmarks.

About 10 will play and bookmarks and videos work.

But after this number of videos play, no other video will work. 

The bottom cursor timeline jumps to the bookmark spot, but the video does not follow; and the play/pause button in the lower left does not respond.  The first 10 videos continue to work fine -- both play/pause/bookmark function.  But no new video will play after opening the initial 10.

I have tried using few videos (same issue with about 15 videos).  The videos work fine at one per page.  I have tried "page-in-page" plugin to distribute code/videos to other pages in groups (and avoid long code on one page).  To no avail.

Thank you very much.