Difficult question, what are you doing with the video later in the process?
"Lossless" and "uncompressed" are two different things.
"Lossless" means that the decompressed file should be identical to the state of the file before compression. Think of how a Word document can be compressed using (lossless) ZIP and when you decompress it all the text and formatting of the Word document is intact.
On the other hand, every time you save an image as a JPEG, it gets compressed and looses quality.
"Uncompressed" means that the file shouldn't use compression at all.
A common lossless compression is using QuickTime Animation @ 100%. For smaller (but lossy) files you can use QuickTime PhotoJPEG @100% which has very slight compression.
- Jonas Hummelstrand