On both Firefox and Chrome, when I hover over either of the videos, the thin dividing line disappears, and it's not clear which video I'm looking at. Albeit they are "supposed to" look very similar, I still don't know whether I'm watching the original or the compressed one.

Typically in similar sites, I've seen a draggable divider that lets the user specify how to horizontally divide the frame between the two comparable videos.

Do you process an included audio track as well?

Audio is included. The line disappears because they are actually two videos, and I was showing how flawlessly they blend. Each half is either compressed or the original.

Compressify's developer here. Would love any feedback on the site and video results. Sorry if the server is slow, it's getting the product hunt hug of death.

Awesome product! Any plans to open it up to larger sized video files? (I'd pay for that!)

Yep! Email me at compressifyapi @ gmail.com with details about your target videos.