...thanks again - and yes, it is probably a miserable codec. It's a shame that Sketchup is willing to accept that a laborious task (by man and machine) is useless by this shortcoming.
Luckily you introduced and remembered me to the "single frame method" đź‘Ť I put the frame bundles directly into my timeline within Adobe Premiere Pro and it worked perfectly and above all in the quality to be expected right from the start...