Instagram requires login. Twitter does not.

Twitter started requiring login post acquisition. Never did before.

I just closed the login prompt for the insta link, and watched the video. So it does prompt one to login, but it definitely isn't required to watch the video from that link

I'd have sworn I was unable to view tweets recently without logging in. But maybe I was wrong.

Instagram lets me view the video without login (I have to click the 'X' in the top-right of annoying popup, but I can watch it without logging in).