the iPad (or iPhone) shoots video it embeds info that says what it the
top of the video. But other PC software often doesn't recognize that
The best way to prevent this problem with video and to make sure a PC always plays the video upright is to shoot video with your ipad so that the "home" power button is on the right side as you shoot.
If you have video that is "off", I'm going to look at some rotating aps, but for just changing it to view......At Hesston we have the free VLC media player on all computers and in it you can rotate the video to the correction orientation. Here are those step by step instructions
A quick fix to play a "wrong angle" video in the classroom is to hookup your iPad to the projector via the laptop VGA cable (with ipad to VGA adaptor). Then you can rotate the iPad and get the video correct. For iPad audio, you will need to hook up the audio cable.