I ran into the same issue a while back. I follow this yoga instructor who posts quick routines, and when I’m at the park or gym, my connection drops constantly. Screenshots were useless and recording on my phone just looked grainy. I ended up trying https://peekviewer.com/instagram-downloader/  and it worked surprisingly well. I could save the videos in good quality, watch them offline, and still keep up with my practice without fumbling with poor recordings.