Hi Matt, 

Thanks very much for the advice. I've 'solved' the problem since then but I'm not 100% sure how I did it yet. That's why I hadn't posted a reply until now! 

I re-encoded the video (in Shotcut), shortened the file name, reinstalled the media component and cleaned up the JSON (removing anything redundant) and that seemed to fix it but wasn't able to replicate the fix on a colleague's machine. 

 Thanks!