youtube-dl and youtube through free software [Was: Fwd: Re: praising our moderators]

Hi, I received this message from g-m-d, and I’d like to know your opinion 
about it.  First of all (as last suggestion) he suggests using free-JS 
“frontend” to youtube, which likely can only at best themselves work by 
running the less non-free software for downloading videos from youtube… 
isn’t that as wrong as using it directly? I mean, it has even the added 
downside of looking like SaaSS and requiring an added intermediary and 
being a centralized solution… what do you think about it?

Also about youtube-dl apparently it’s like I thought and it only executes 
a branchless (hence turing-incomplete) subset of javascript to compute a 
signature for the video to be downloaded… isn’t that the Right Thing? how 
is that different from automated reverse engineering?

Because: the work-load-heavier alternative would be to look at the 
extracted function alone, and rewrite it from that small subset of js into 
python by hand (what youtube-dl apparently already does, but in an 
automated manner)… but this subset is automatically generated, and has no 
meaning… it’s like a programming-language-based encryption… so isn’t that 
like doing manually what is done automatically? since this is 
automatically generated, and has no capabilities (other than hiding 
information), doesn’t it have “no meaning” as a program? doesn’t this sort 
of sub-“evaluation” is something akin to “decrypting”?