As always, the Bishops have the final and official word on such matters. I am not aware of what proceedings, if any, are being undertaken at this stage by ecclesial authorities to investigate this particular case. It's still very recent news.
I personally find no reason to be skeptical about the idea of the Holy Virgin appearing on the domes of her church during the blessed Nativity Fast, especially at this time. Her appearance as such has been confirmed by the Church in the past (e.g. her appearance at Zeitoun).
The video footage, coming as it does from a camera phone, isn't the best of quality, but it is clear enough in my opinion--and in the opinion of the commentators, who btw are not Christian, and who do in fact briefly note and proceed to reply to some obvious typical objections to the footage. The display at 4:50-4:54 shows that the illumined figure is, contrary to the illumined crosses, not attached to the church's structure. As is clearer to the eye witnesses, the light of the illumined figure differs remarkably from the dull yellow light of the crosses--it is a mixture of a bright blue and white light (the blue light presumably corresponding to her blue attire); eye-witnesses have furthermore noted that it does not retain a fixed position.