no, you can download the videos using keepvid.com. When they download they will come in .flv format. Then she can use VLC Media player (www.videolan.org) to play the .flv video or they can use a website such as zanmar.com or media-convert.com to convert the .flv to a mpeg or avi video that you can watch on windows media player. Once its downloaded no internet is needed.
Youtube is blocked at many of the schools in the US. Some schools allow teachers access but mine does not. We teachers still use youtube videos. We download them at home using zamzar, keepvid, or TubeTV for Macs. We then put them on a flash drive and bring them to school. VLC works great for playing the flv videos. Your teacher does not need to have Internet connection once she/he has downloaded the video.