This is a really cool idea. I think the limitations are that you can only make filament rolls that are small enough to fit on your bed, and the precision with which the colours match the intended part depends on how much oozes out when you're priming the nozzle.

I noticed that some of the parts shown in the video appear to have a wipe tower next to them. Presumably this is because the G-code was generated with Cura or similar, but given that the filament is one continuous piece with colour changes in exactly the right places, it seems like you could skip the wipe tower? Or maybe it's better to keep the wipe tower because it reduces the precision required in priming the nozzle?