I'm making a film in 30fps, 720p. I'm going to be scanning photos for the project to use in Final Cut Pro, the software I use for editing. What resolution should I scan on? I imagine past a certain point, it doesnt make a difference how detailed it is, and I dont want to do more detailed than necessary since it'll take a long time.

Any thoughts?

Depends on the size of your photo. Typical 9x5" will give you 2700x1500 pixels when scanned in 300 dpi. Just multiply the resolution times size to get the pixel size that you want. Of course unless you are doing with raster (offset printing), then 150 dpi is most probably the resolution that you're looking for.

DPI means "dots per inch", but there are no inches in video, so DPI becomes irrelevant.

720P is 1280 pixels wide by 720 pixels high, therefore you want all of your pictures to be at least 1280x720. If you want to do moves (ala Ken Burns) on the photos, then you should probably double that, meaning at least 2560 pixels wide or 1440 pixels high.

What resolution should I scan on?

DPI means "dots per inch", but there are no inches in video, so DPI becomes irrelevant.

Arnie is SORT of right, in the sense that video doesn't have DPI. Having said that, what Noam asked is "What DPI should I scan?"

The answer is:
In order to give you the requisite number of pixels for what you intend to do, as explained by Arnie.

If you want to JUST fill a 1280x720 pixel frame with a landscape 8x10" print image you need to do some math:

The LONG side in this case is 10" and needs to be 1280 pixels to JUST fit so you need to scan at 128 dpi. Now check to make sure you have enough pixels the OTHER way...

8" x 128 dpi = 1024, which is MORE than 720 pixels and will require you to crop approximately 300 pixels from the top and/or bottom of the frame to fit EXACTLY.

Things get more complicated if you want to use an image with an orientation OTHER than the "landscape" of video, especially 16:9.

Of course, this assumes you are looking for a Scale of 100% of your image in the timeline to avoid aliasing artifacts. I can OFTEN get away with scaling up to 200% with still images, depending on content, especially if I add a VERY small Gaussian Blur effect...

So, I'd like to scan at 4000x4000 pixels so I have room to zoom in if wanted.

I have a friend with this printer and I can use it: Brother MFC-490CW All-in-one (printer/scanner/copier/fax) / by Manufacturer / Printers & All-in-ones / Laser & Ink-jet, All-in-Ones & Printers Full Catalogue (http://www.find-printers.com/printers/manufacturers/pos/brother_mfc-490cw)

Can i do that with this printer? It only lists DPI in its specs, saying that it's scanning resolution is 1200x2400 dpi and the enhanced resolution is 19200x19200 dpi. Will this do?

What is the physical size of your photos? Without giving us this information there is no way we can answer.

Besides, using such cheap scanners at resolution higher than 300 dpi usually results in simply blurred image, not more data, and also there is a physical limit of detail that can be seen on a simple photo print. Usually it is pointless to go more than 250-300 dpi.

All different sizes. Some are standard size photographs (you know, the rectangular kind you get from the photo store...i know that's not specific), some are 8.5X11 sheets of paper and some are irregular sized newspaper clippings.