Recommended size for movie - online experiment

URL of experiment: https://pavlovia.org/henning/movie-test

Description of the problem: Hi, first of many thanks for providing this software, I am really excited about taking my research online and love the seamless integration of pavlovia and builder.

We want to present short video clips (about 1 sec each), and participants make a button response for each video. I have created a short dummy where 3 different videos (of low, medium and high quality) are played. They play fine when I try it, but I guess different participants will have different bandwidths.

Is there a recommendation about the maximum file size so that videos still play fluently online without dropping frames?
low quality: about 50kb
medium: about 600kb
high: 1.9 MB

videos are encoded as h264 mp4s, as recommended elsewhere

Kind regards,
Henning