Is a dancing crew dangerous?
Well I suppose the answer depends on whether or not the flight crew are good dancers: If my uncoordinated self was trying to bust a move in an airline cabin I'd probably wind up kicking someone in the face, but these folks seem to be doing OK.
I can only assume dance lessons are part of SpiceJet's crew training program :-)



Alright, in all seriousness - there is increased risk any time every person onboard isn't securely strapped into their seats. There have been incidents (recent ones) where flight crew walking about the cabin have been injured due to unexpected turbulence, and those same unrestrained people can essentially become human projectiles to injure others onboard.
That said I personally don't think the cabin crew doing a mid-flight dance routine poses a significant safety risk.

The fact that one of the pilots was out of the cockpit recording it is slightly more questionable, and may be what has the DGCA upset in this situation. While there are procedures for having one pilot off the flight deck those provisions are generally for necessary things (like a trip to the bathroom, or investigating a systems fault). The intent is for the cockpit to be manned by two qualified pilots at all times.
If an emergency were to have happened during this dance routine the pilot we see in the video would have had to get back to the cockpit, strap in, and put on a headset (&amp; possibly an oxygen mask) before being of much use.