okay, since this is your first mix, i am gonna give you a thorough analysis of your work. first of all, a mix works best when the music you choose is something that you really like and you are into at that time. For my mixes i listen to the music at least 100 times when making the mix, and most of the time i hate the music after i am done with the mix because i have listened to it so many times. And classical music can work for a mix, its just how you put the clips together to make it go with the music. I did a mix not to long ago using classical music.
http://uk.youtube.com/watch?v=zXjICI9KsRY
what you need to work on, is the pace of the mix, for about five seconds( 25 to 30) your videos went really well with the music, and you have to work on that. As for the clips, i think you got most of it from other mixes so the makes the quality of the clips poorer if you use it again. so i suggest downloading HQ clips for the basketball clips section. First mixes are rarely great, but what matters is you started and the mixes can only get better from now. so good luck!