Issue while downloading a file from youtube via IDM

I download a file (video) from youtube via IDM. What happens, it downloads completely but while running the video, I find that it isn't proper. The video won't be complete. for ex., a 10 minutes video which I downloaded now runs for 10 seconds only and then stops. So, may times I download the same file (which obviously takes a long time and requires patience) and once some how it works.
I AM IN A BIG PROBLEM.
This is happening since 20 days when I installed AVG Internet Security 2013 (cracked version). It had blocked IDM from interacting with internet(on account of broken signature or something like that) but later changed the set up in firewall and allowed IDM to interact. But since then this problem I am getting. IT IS A VERY BIG PROBLEM FOR ME. PLEASE RESOLVE SOON. Before I installed AVG it was downloading properly via IDM.

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