Use a product such as net nanny.
As free FLV Downloader, can download FLV files from any sites easily.
Free Video Sites For iPod, most papular video webs for ipod.
Specializing in formats meant for portable devices, FLV Converter also supports.
It can also block entirely
http://www.netnanny.com/alt4
Set computer B to a manual IP address, and don’t enter any DNS entries. It can still share locally with MS sharing, but any URL query to internet will fail (IP query will work, but “B” has to find the IP first…hard to do without DNS)
No…you don’t want to do it the way Adrian says. If you do, every time you require a DNS query, it’s going to sit there, and have to time out to NETBIOS first. A better way is to harcode Machine B’s IP address, but don’t give it a Default Gateway. If you do that, it will still be able to access anything on the local network, but nothing OFF of the local network.
I got a good one for you. Home network, wireless router. Enable file sharing between computer A & computer B but prevent computer B from all internet connectivity. Any ideas?