This guidance is not unique to hypercasual, but applies here. From an advertiser's perspective playable and video are most often part of the same inventory pool and should not be treated wildly differently from each other. If you use playables and video within the same campaign on an Rewarded video SDK network, whichever has the highest IPM will rise to the top and be served the most.
In my experience with hypercasual-adjacent titles playables can very often have notably higher IPM than videos so will often rise to the top performing slot, which in turn can support lower CPIs than your video ads. In one recent case of ours the best playable on a network was >4 IPM and top video video was about half of that.
There is a downside though, in that often playables will generate lower post-install KPIs (ROAS etc) than video within the same inventory pool. Due to this, one best practice is to create paralell campaigns for video and playables within the same network, and optimize each seperately. Particularly in networks that do not support publisher level bidding you may often find it makes sense to run playables at a lower CPI (due to their trend towards higher IPM but lower ROAS).