Is it possible to download videos or pictures from computer to Nintendo DS besides video games?
If so where do they usually end up being in the DS cause I can't seem to find some videos or pictures that I think are hidden from a friend of mine were do I go to find out? Anyone help.. thank you

Don't think so. Perhaps through the slot for games...

The Person That I Lend My Ds To Bought A Slot (I Think) Or Some Sort Of Memory Card That You Insert Into The Ds And Can Download Any Games For Free.. Could That Be Used Also For Videos Or Pics.? Is Their Such Thing As That For The Ds?

There is no easy way to do this... except to buy a Sony PSP =P
The Nintendo DS has no internal memory.

The card your friend has is primarily used to download and play games with, but with the right card or some tweaking (AND the right card), it may be possible.

Here is the round about way to do this with an adapter according to the interweb:
You need a homebrew app like moonshell or DSorganize. Hopefully you bought an adapter that has something like moonshell already installed. If so it should read your pictures simply by drag and drop onto the SD card. A lot depends on the adapter you bought (M3 Real, cycloDS, r4DS, etc)

No you can not download videos or pics because the ds is meant for playing games that's why I have a psp. I just wrote all this on my psp. Please rate my answers.

I think that on the R4 you can have other stuff besides games. I myself have an R4, but Ive never tried getting pictures into it

With the R4 and TTDS, you can have pictures and music if you want to, there are the different options. But I keep my pictures on my computer as well as music. I leave the games for the ds.