Best Way to Avoid Blurry Videos

As for another viewpoint . . .

I usually "gently and friendly" push back on courses being so big on the screen or video being fullscreen.  Some things have to be but others don't (e.g., a talking head of a speaker)

I prefer using a player size that works well both on PC screens and on tablets like the iPad.  For that I use 960 x 540 (when using any of the Articulate bottom controls or nav) or 960 x 600 (when using no bottom controls and supplying my own nav).  Those sizes look good both on PCs/notebooks and on iPads with a minimal of scaling.  I also get smaller courses (helpful when some LMS's restrict total storage size) and "friendlier courses" to download on the network.

I'll then produce my source videos at hi-res and something like 1920 x 1080 and I'll let SL360 size them down to what I need.  So far, knock on wood, this also always worked for me.  In those cases it does not, I try to size the source video as best I can to its onscreen size in Storyline.