I actually copied and pasted most of it from other sources (which I've listed on the page).
The playlists are "saved" by sharing them - each playlist exists only as a URL containing a comma separated list of video IDs.
I've been sharing on Twitter using the #cueyoutube hashtag.
Unfortunately, however, my primary webserver is down due to a drive failure - I'm waiting for the VPS image to copy to a new host now. Bummer :( Should be back up in about an hour with any luck.
There are some suggestions from people over at http://cueyoutube.uservoice.com/
I really want to only work on the site in response to user demand, you know? Like I want to keep it as an MVP always. If people like it, then they will use it and make suggestions and I'll react to that.
I'm really enjoying the "throwaway" nature of the playlists themselves (ie. you don't login, you don't give them a name, you don't "save" them, you just create, share and move on with your life), but also the "throwaway" nature of the project - it's good to have something that's useful but that I'm not so heavily invested in (unlike Decal, which I'm like, totally invested in to the point of insanity).
