Video conversion, codecs and wrappers are actually really complicated.

But there is no reason why you shouldn't be able to do what you want.

OK, so a lot of your format will depend on what your source is. You will waste space converting a low res video to a higher res, and you could lose quality on an hd video if you don't format it to hd.

For reference standard TV widescreen in the u.s. is NTSC, which runs at 30fps. Anything faster than 24 will appear as liquid motion to the human eye. A resolution of NTSC is 720x480. If you just wanted to shoot from the hip, you could convert to 30fps at 720x480 and it would work. But, depending on your source, you may be losing quality or wasting space.

The standard widescreen ratio for TV currently is 16/9, so any resolution that is at this ratio will scale on your tv properly.

Video conversion times are reduced with a powerful pc. There are some converters that can use your gpu and are able to transcode a full movie in just a few minutes.

EDIT: For audio, a lot depends on the codec.. mp3 you will want at least 192k, ACC I would say at least 128.

What converter are you using?

http://en.wikipedia.org/wiki/Ntsc
http://en.wikipedia.org/wiki/DVD-Video

EDIT2: I'm obviously no expert on this and I can only share with you what I've found out and what I have observed to work well for me. If you find out new or contradicting information, please do not take this post as word of god or anything like that.

Scary because I'm probably the biggest computer dolt on the planet.

I use a free converter that actually doesn't even have a name... at least it doesn't when you open the program. It's very bare bones, but that works for me since it's a lot easier for me to understand computer stuff that's bare bones. I got it from topsevenreviews.com but I can't seem to find the same thing on their website now, though I think it was this one since it looks so familiar, and for the desktop icon it uses that same "f" in a red circle symbol that Macromedia Flash uses...

http://www.topsevenreviews.com/free-flv-to-mp4-converter.html

When I clicked on the "screenshot" link under the photo though it doesn't look at all like what mine does, but they may have updated it since so I don't know.

I always used the output under the list for "MPEG-4 Video (*.mp4)" since all the other ones I either didn't understand what they meant or for specific brands and devices like Ipod or Apple or whatever. Then there's a "settings" button where you can put in all the various video and audio settings you want but I never used it since I have no idea what they mean.

I also use Nero (came free with the computer) to burn the converted .mp4 files onto disks so I can watch them on my tv with the DVD player. I've noticed that anything I download from YouTube that I don't have to convert by choosing to download the .mp4 option I can burn to a DVD, and when I watch it on the tv it fills the whole screen. Even though I figured out how to switch the settings through Nero to 720x480 and 16/9 though it takes up more space on the disk it doesn't matter when it comes to how much of the screen the movie uses... most of the time I still get those damn black blank sections at the top and bottom that are sometimes so fat that the picture on the tv looks like a long skinny thing that is just weird looking to watch a film.

Very occasionally I get a video that uses PAL, but Nero lets me switch it NTSC with no problem.

I piddled around in the settings section of my converter and it uses ACC - that's the only option - though I don't know what that means.

I've been wondering if these were settings from the original .flv file, but I figured I could change them since all the .mp4 files I get from YouTube I notice always are set to something so that the video takes up the whole screen on the tv. Though I DO always set them to 720x480 and 16/9 which is all that Nero lets you do as far as video and audio settings the video still comes out to whatever the original file must have been... sometimes it fills the whole screen, sometimes it gets really ridiculous fat blank black space at the top and bottom, and sometimes it's less blank black space to the picture doesn't look so bad, but I'd still rather that it filled up the whole screen.

Thanks for the links. I'll try plowing through them and see if I can understand any of it.

Sorry, I'm at work and cant give you a full response, but I will.

In the meantime, if you can, grab a copy of handbrake. http://handbrake.fr/

It's a very popular and capable video converter. It can handle flv -> mp4.

Those black boxes are related to the resolution, 720x480 is 4:3 so if you use 720x480 in a widescreen format you get black bars unless you use DVD modes because DVD has non-square pixels.

If you use 854 x 480 is 16 NTSC with the black boxes

Why not burn your .flv files onto DVD directly, and the fact is MP4 is not a standard format that DVD reads.

How to Burn FLV to DVD on Mac/ Windows

Have a look at this article, you dont need to convert the file to a dvd format then use another tool to burn them. The program mentioned above handles these all in one place.

Which is really the point of my downloading and burning. Besides, a lot of the settings problems may likely be in the original FLV's.