UPDATE: False alarm, Lynda Albertson tells me that after some searching, she found out that the "new" video you saw on Palmyra is from May 20, 2015, the day Daesh overran Tadmor/Palmyra. Thanks, it is worth looking at her comments on this topic on the ARCA blog Palmyra - An example of when traffic whoring and page view metrics are more important than accuracy.
While accepting the criticism, I'd point out that the video to which I link is not the same as the one to which she refers, (unless that has been now replaced by another) and is not a fragment from it. The video to which I referred was posted on 10th March on an account of Khaled AL Homsi which I took to be the same person as Khaled AL Homsi (@PalmyraPioneer)on Twitter (media and archaeologists, human rights activist from Palmyra in Syria and based in Homs (?) . who refers to some ongoing attacks at the time . In view of the uncertainty about what we are seeing here, I'll strike this through.