Thanks for this, it works great in Finder, but in Forklift and Bloom I'm still seeing a generic icon and not a thumbnail. I don't know whether the problem is theirs or QuickLookVideo, so will happily get in contact with them, if that's the case..

(BTW I also tried the other recommended thumbnail / quicklook app, namely Mkv Quicklook, which does show thumbnails in Finder, Forklift and Bloom, however in my case, they always appear upside down)