Dave: I tried modifying the MP4 file with iMovie and saving it under a different name.
Still no joy. It shows Rainer Cooney starting an original Spyder - Geriatric 6 volt starter and all. Looks great on my Macbook but the Crowdstack site gives me an error when I try to load it.
I give up. Poirot is on PBS. I'm outa here.