Well, the ceiling was not completely overcast as one can see multiple times in the video. I wouldnt therefore dismiss this as unsafe in general, but as always you have to know what you're doing. These holes might close, leaving you with a solid cloud top.
Reminds me of a flight from Santa Catalina back to Torrance, where some coastal clouds were developing. First, we tried scud-running in poor visibility, but then we decided to go on top (was sort of a 7.5/8 cloud base). In case of an emergency, you could still pick a hole through the cloud layer and we knew the clouds ended pretty much at the coastline, therefore in this particular situation it was actually safer to fly on top.
But again, I dont want to solicit going on top in general, all depends on the circumstances.