Thanks so much for your response - it's definitely helpful.

I've been able to get it to work and managed to do a sample run with sets of videos from two separate participants by assigning each participant the same order value but assigning each participant a different value for within-subjects randomization within an experiment file.

But, the question remains about how to make sure that raters will not end up viewing the videos for all participants. As I mentioned before, there are about 40 different participant videos - there's no way that raters will be able to handle viewing all of them.

So, what would I need to do so that raters would view a random selection of 20 of the participants out of the 40?

Thanks for your help!