There are probably formatted in the Adobe Flash format and the iPad doesn't support Flash. You could try SkyFire, on the apps store, I understand that you pick a video from the site in SkyFire and it first converts if from Flash to HTML5, which the Ipad can play, and then sends it down to you a few seconds later. On your PC, if you right click on the video, you will see if it's done in Adobe Flash listed, if it is, try SkyFire.