The main purpose of the DMCA is to make it illegal for anyone to "crack" or otherwise circumvent copy-protection schemes used on digital content. Most commercially-produced DVDs use an encyption scheme called "Content Scramble System"; The act makes it illegal to decrypt DVDs using software other than a licensed DVD player.
In the video above, the Motion Picture Association of America (those friendly folks who make the "DON'T YOU DARE DOWNLOAD THIS!!!!" videos you see at the theater or on your DVDs) is trying to convince the US Copyright Office that teachers shouldn't be given an exemption from the DMCA for the purpose of educational use of prerecorded material.
Note that there's no question of the legitimacy of educational use of copyrighted material: that clearly falls under fair use. Teachers can play clips, play entire movies, cut together music videos, whatever... What's under scrutiny is the methods teachers are allowed to use in aquiring the copyrighted material--whether they should be able to decrypt DVDs using methods that violate the DMCA. The MPAA is arguing that it is more reasonable for a teacher to use a camcorder to record video off of a computer monitor or TV screen than it is to decrypt the DVD using a computer and commonly available, easy-to-use software.
Zee mind, she boggles!!!