I would look no further than Marc Anthony's website: http://www.marcanthonyonline.com/
These are in streaming format.
If you want to actually download them onto your computer, you would need to pay for them and sites like www.mp3.com would offer this service.
If you already own the video, but are trying to watch them on your computer, you might consider a file sharing program. Slyck is a nice guide for file sharing, but be sure you understand the law before engaging in such activity.