It appears that there was a considerable amount of contamination, either snow, ice, frost, or a mix thereof, on the wing when the takeoff roll started, and that is not considered safe under any current standards I'm aware of.
There are markings on the top of the wing for the 737 Next Generation series that define an area where cold-soaked fuel frost is acceptable up to a defined thickness, but the area covered by the contamination in the video extended beyond those markings, so even if it was CSFF (which I doubt, given what's shown late in the video), it was still more than what's allowed.
Late in the video with the aircraft flying, we see that much of the ice is no longer present, which means that it detached from the wing at some point. If it was dry snow that blew off in the first 10 or 20 knots of the takeoff roll, that's no big deal, but you don't see the ice gone until late in the video -- this isn't simply dry snow. Plus, you still see significant patches of ice adhering to the wing at the end of the video -- which suggests that it isn't CSFF nor dry snow, but ice.
The current accepted standards of safety in commercial aviation don't permit taking off with any ice adhering to the wing, and from what is shown in the video, it certainly looks like that's what was done here. (Disclaimer, I'm no expert on watching u-tube videos of ice-covered wings, so there may be more going on here than is apparent on first or second viewing.) IF that's correct, then I'd have to agree with the title of the video, that this was unsafe.
The standards of safety allow for a lot of margin, so that when mistakes get made they are still likely to be survivable, and it looks like that's how things turned out here. Things were done wrong but everybody made it out okay. But... what if one more thing had gone wrong? What if they'd lost an engine at rotation? Would the aircraft have been able to climb out with one engine & the wings in this condition? Or would these guys have been headline news of a crash out of Sarajevo that killed all on board plus how many more on the ground?
No, this looks pretty far out of bounds to me.