I've downloaded TV shows from the internet before which were typically around 40 min shows and compressed into a 350 mb AVI. What I would like to know is if this is being done with a TV capture card and special software? If so, could someone point me in the right direction as to what would be the best or close to the best capture card and also which software should I be using. Thanks.
The most likely case is capturing the format to your computer then encoding it to Divx/Xvid. For capturing off cable TV, yes you would need a TV Tuner card. There are other ways but they require purchasing hardware as well. I won't get into the other choices since they run through firewire and require more experience in the field of video encoding and what not.
Your best bet would be to buy a capture card and capture them onto your computer. Then encode them into Divx/Xvid for the highest quality possible. This will give you the highest quality possible although it would take more effort and research into understanding compression and the different formats.
But if quality isn't a very big deal for you...You can use this method...
This way you'll capture directly to divx and can store files a lot faster then letting each file encode. Encoding is what takes the most time when understand formats and quality differences. But this should be fine for mass storage of TV shows. If the shows you have on your computer are extremely crisp and clear...Chances are they were DVD rips. Basically taking a DVD and popping it into your dvd rom drive. Ripping the vob's (Dvd file format) and taking steps on encoding them to divx/xvid. This method provides the best quality possible but I wouldn't recommend it to anyone who isn't really interested in completely learning video codecs and encoding in and out. The only downside to this method is the files can be larger then high quality encodes which actually take time to analyze the file. The quality of this method is also probably going to end up worse then high quality encodes. The reason is when you capture video as it streams the computer is basically running the steam into the Divx/Xvid format. But since it has to do it real time it basically just outputs the data with the bitrate you've selected. When it comes to files that are master quality which have been captured or ripped before hand...you can setup a 2 pass encode to analyze the file to see what segments need the most data. This provides the highest quality possible if you know what you're doing...
For the link I posted all you need is a TV capture card which you can purchase from the store. It basically lets you plug your cable into your computer. You also need the software Virtual Dub which is a powerful video processing application...It's completely free as well. Which makes it one of the most used applications for Xvid/Divx compression. I would recommend this method if you don't want to spend time reading and understanding the terminology and aspects of video encoding.
Hope this helps you out. If you have any questions...feel free to ask.