I have requested for the video solution for some questions of my snap test series. Where i can get it????

they will attach it under the question itself if there is enough demand for it.

I scored 252 in NMAT this year. Should I appear for a reattempt?

Look, as long as all your sectional scores are above 75, then you should be completely safe for even Mumbai. Only if one section has a score lower than 70, and you know that you can get it up by 10-15 marks at the the very least, you should give a retake. Otherwise, just wait for a call from NMIMS Mumbai.