I don't know if it would be a problem if you just upload a video because I don't know the website you're talking about and what the potential buyers do expect there.
Why don't you take a good [free?] obfuscator and upload the obfuscated application? E.g.
ConfuserEx[
^]
Consider this: Would somebody who is willing to go through the hassle of de-obfuscating AND identifiying the meaning of all meaninglessly named identifiers and renaming them buy your sourcecode if he hadn't the chance to deobfuscate it? Probably not! Because it would take him a lot of effort and somebody who has the money to buy it would rather buy it than go through that trouble.