Youtube advice needed

I still dont totally get why people want to open 100's or 1000's of accounts but thats maybe by the by, i would love to know how to promote a playlist within youtube, can it be promoted within youtube or does it need external backlinks.
Does the process of making friends on a channel prove to youtube that this is a healthy channel?
I believe that creating playlists acts as a kind of backlink within youtube to the original videos which then i guess lots of channels = lots of playlists = lots of backlinks to original videos?
I believe Likes do have a positive effect but possibly the lowest effect and comments are very healthy for a video slightly helping.
Any ones advice would be highly welcome.

They need it for mass upload. If you put all of your videos in one account, there is a huge tendancy that your account might get banned and you will loose time and money.

Ok i can see the problem for mass video uploaders, because their technique is truly black hat, so on the white hat front if you looking for long term success i would be really interested in how to rank playlists as well as the original video and has anybody had success using this technique

Create a playlist max of 10 or 5 then put a link on another video on the description of each. It could go viral.

I know that in playlists you can edit and put tags and description
so you are saying put in 5 - 10 videos in the playlist, then description and tags, then create another playlist on another channel? or a new playlist from same channel.
I dont think they will go viral as its kind of a niche market at the mo, top video in section has 35,000 views but i know competition are building backlinks to videos to make them rank in google where there are much larger searches