The videos are working online in your dummy experiment? Maybe you could try building it up until it either replaces your original experiment or you find out which step breaks it.
According to ChatGPT, there are a couple of possibilities for the error:
Media Loading Aborted by the User
If a media resource (like an audio or video file) is being fetched and the user navigates away, the browser may abort the loading process, resulting in this error. Network Issues or Browser Policies
Some browsers may abort fetch requests due to security policies, network disconnections, or other resource constraints.
I wouldn’t expect there to be an issue with this video – it is H264 encoded and not too big. I wonder if there are specific files that fail. You could try using a print statement to check the value for video1 at the point of failure.