Hi Husain, and welcome to the forum.
I've done a few bits like this myself - film a local community event and put it up on YouTube for the community to enjoy. You've posted it in the section for constructive criticism so i'll try to give some.
With a film like this, you wnat to give as many people as possible a chance to see themselves as well as the action. So, film the action and the people and throw out the stuff which doesn't really add anything. A few secons of the fireworks at the beginning and end would have been enough - you didn't have a particularly good view of them so several secods doesn't really add anything.
I found a lot of the transitions very harsh. You take one section of the girl singing and then cut audio and video without any consideration of the music or even the beat. Ditto the drums. It is aways worth recoding at least one piece of music all the way through to use as a backdrop. You can then fade it out as you cut to one section of the girl singing, cut away from that to another shot, fade the girl's voice out and your "backdrop" piece up, then do the reverse to fade i the next part of the girl singing. Even better would be to record a section of the girl's performance. Show part of it, drop some cutaways in whilst you change camera angle/framing, then bring the girl back in. It's all really about making the thing flow more smoothly.
I liked the images you had - the colour was very warm (what camera?) I liked that you got some good close ups of the girl singing. Next time try to get some other "incidental" close-ups that you can use as cutaways (a particular decoration, a child's nand in a parent's hand, an abandoned Santa hat) all of these things add atmosphere and give you the opportunity to cover a "glitch" or cover jump cuts.
I'm sure others will add their thoughts, but keep at it. Have you thought about joining Harrow Cine & Video Society (one of the few clubs still retaining the "cine" in their name)? They are one of many clubs throughout the land affilliated to the IAC. If you do go along, tell the Tim from Staines Video Makers recommended you
Great! Very helpful feedback - all points noted - I used Sony CX730E on this occasion - Sony NX5E was too bulky for the event. Would keep HC&VS in mind. Thanks, Tim!