The question was about "reading" the projected negative I think ? Well that depends on the neg - the more complicated the shot or the lower the contrast, the harder it gets. Of course, by that stage most people have already seen the contact sheet, so it is maybe a combination of the two.
The ambrotypes, and shining-a-light-on-the-neg sort of idea, work by light reflected off the silver in the emulsion, so to try that use a slightly thinner neg. It can look interesting on 5x4, mounted on gloss black perspex for example, especially with a little collection of them mounted together. Best made via a contact, or projection, print on to ortho film as a safelight makes it easier to see what is going on.