Just got a new galaxy s3 and have a video transfer question

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http://androidforums.com – I have some mkv videos I would like to play on my new s3. I downloaded mxplayer but what should be the simplest part is giving me a massive headache. I can not figure out how to transfer the files over. I connected it to my win7 pc via usb and drag and drop would not work(progress bar in copying would never fill up). Tried sync with windows media player and that stalls out at 85% on every file. Tried using kies and about 50% into it it gets interrupted and stops and for some wont even start the transfer at all. Kinda at my wits end here and regretting getting this thing. Is there no way I can (General)