+1 to this feature request.
I'm on the same boat where I have to download videos locally since streaming is not an option. With 3 download limit, 'Premium + Script' doesn't provide value for me compared to regular 'Premium' since the cost is $10 more, but 3 scripts generally cost less than that (assuming $2.99 per regular buy). I do understand the limit should be in place to protect scripters.
From a business perspective, this should be a feasible feature since another cohort within 'Premium+Script' is already using this (stream video + stream script), so adding it for my cohort (local video + stream script) is not different by much. One possible con is that my cohort can tend to download larger videos (i.e. original files) so that bandwidth cost needs to be considered.
From a technical perspective, there will be a bit of work to match a local video file name to the correct script. Besides that I don't see any difference between "local video + stream script" vs "stream video + stream script" since (at least for the handy) scripts are sent to the machine, now it will only differ in its origin location (sent in from SLR servers instead of from my headset).