Tempo Change / Bar-by-bar synchronization

It would be great to be able to add tempo changes or synchronize each bar or even each beat to a Youtube Video timestamp. How else to compensate for fermatas? I’m trying to understand what’s going on in https://www.youtube.com/watch?v=Xp3IHBSyZKY Ubi Caritas by Ola Gjelio: http://www.hooktheory.com/hookpad/view/EApYaMXyQIju

Also, why the cutoff at 50 bpm? At a stated 52 pbm Ubi Caritas is close this limit (although as performed in the youtube video, its closer to 63 pbm). Of course, it also shows the need for signature changes after only 3 bars - I see from another forum post that this is already a planned future feature.

Thanks and best regards