I found the solution here:
"Hi @tim, this is a syntax error in the JS code compiler. It relates to the units param used for your movie stim. This was a bug that has been fixed for the next release of PsychoPy, but in the mean time, I suggest you either set the units to “from exp settings” and resize your video accordingly, or manually edit the JS code to fix the syntax error (specifically line 305 where the units are set for the movie stim). To do this, you will need to do the following:
- Go to Experiment Settings > Online and set “Export HTML” to “manually”
- Open your JS file (found in the HTML folder) and change line 305 so units in the movie stim are set using a colon, not an equals sign e.g., should be
units : 'cm'. - Save file and resync with Pavlovia
If you choose to manually edit the file, then two things to remember. 1) if you make changes to the experiment, you will have to manually recompile the experiment so the new changes are written to the JS (done using the File > Export HTML from Builder), 2) your manual changes will be overwritten if you recompile your task."