how to play youtube videos back to back ?

Many people don't know youtube already has a playlist feature that can play a list of favorite songs or bunch of videos one after the other. recently i had a bunch of links of some documentary found on some forum almost 15links but playing it all one by one every time is annoying but when i googled on how to play these links automatically back to back i was surprised to see that i was so ignorant that youtube already had this feature and i was opening each link manually all these days.
so how to create and manage youtube play list? first of all create a playlist follow below steps

1. Login to youtube with your google(gmail) account and go to settings from right corner of the portal and select account as shown in below pic

2. Now in opened window click on myvideos and playlist and click on "Create Playlist" an write name of play list, make it private or public and include tag for searching purpose.

3. Click "Save playlist info"

4. You are done now add as many playlist you want to manage your videos.

Now to add videos to playlist there are many different ways follow below simple steps

1. Just search for videos you want, click on the link to open it and find + option below video and click that to add to the que and creates a playlist for you

2. Click on "Add videos to playlist" option on right hand side of the playlist window now you can choose from history or recommendation list generated by youtube.

though above are the two methods to add videos to your playlist i did not find a way to add the list of links or adding video by links to playlist, i dont know why google had missed out such a simple option to add videos to playlist by list of links or youtube link.