This post may be a little off topic.

Honestly, making a virus like that wouldn't be all that difficult. I'm curious, however, how the creator got the information necessary about WebTV/MSNTV in order to only affect that machine. As far as I know, it's not all that easy to write a program or a script that will affect the WebTV, since it's a pretty proprietary operating system. Nice find, though!
I had a webtv for 3 years and I still own one and the fact is there are alot of hackers(if thats what you choose too call them) to dedicated to ripping apart the WebTV box and the WebTV network itself. Alot of cool stuff has been uncovered and its really not that hard. However since I did not do much exploring of the webtv myself I can not give you a direct answers. But if you would like alot of information on webtv hacking look for a site called UlTRICK, or ULTRIX. A person ultrax@webtv.net had a large site full of information on webtv hacking. However alot of it was not aviable to the public. Even still there was alot of information there.(it seems this site is down)

You can look for that site on google if you wish... I'm not sure if you'll find it. also I am contacting some of my webtv friends to see if any of them have the site saved. Here's another good one though of another webtv hacker if your interested.

http://www.geocities.com/wtvsecrets/index2.html

There was also a private newsgroup just for webtv hackers. They at one point discovered how to access these WEBTV private newsgroups some how with a computer(its probably still possible) however I am not sure how. Anyways the newsgroup was alt.discuss.webtv.hacking

Its really easy to make a webtv dial 911, though... REAL easy.