This is an article about how to use the provided tools on YouTube itself to add a link to a video you have uploaded there, not embed a link into videos in general.
Links added by this method are limited in that they can only link between other YouTube content and options.
First and obviously you need an account on YouTube and at least one uploaded video, and preferably two for this exercise.
Go to YouTube and log into your account. Go to a video you have uploaded.
Above the name of the video, you should see a toolbar with the following options: Edit info, Edit video, Edit annotations, Edit captions/subtitles, AudioSwap, Analytics and Promote.
Click on the link that says Edit annotations. This will take you to a new page.
On the right of this page, there is a button which says + Add annotation.
Click this button, and a drop down list will appear with the following options: Speech bubble, Note, Title, Spotlight, Label and Pause.
Click the Note option.
This will bring up an overlay on the video itself, and some more options on the right.
The overlay can be resized and moved on the video, so it's positioned and sized the way you want, but first, define what you want in the note.
You are going to be adding a link, so click the checkbox marked Link. This will bring up some more options.
Clicking the button that appears to the right of the Link checkbox will bring up yet more options: Video, Playlist, Channel, Subscribe, Compose Message, Video Response Upload and YouTube Search Query.
We're going to assume that you want to link to another YouTube video, so click Video.
This is useful for getting viewers to watch more than one of your videos, especially if you have a series you can interlink.
Grab a link for a second video and copy and paste it into the box above where it says Paste a link to a Video.
The link doesn't have to be to one of your own videos of course, but I'm assuming you want to get more traffic to your own rather than other people's.
Entering the links will cause a small button to appear in the note box on the video itself. You can also click Preview link below the link box to check that your link works.
Now enter a note to go with the link button so viewers are prompted to click it. For example, "Click this to see the next video in the series."
You can alter the font size of the text, the font colour, although only between black or white, and the background of the note itself.
Alter the colours and size of the font and the colour of the box until you are happy with it.
Once happy, use the small boxes around the note box to alter its' size, then position it where you want on the video.
You can also define what time the note box appears in the video, and when it's removed (if wanted) by altering the times in the Start and End boxes. The box can remain visible until the video ends if wanted.
The timeline below the video displays when the note is visible to a viewer.
You can also define at what point the linked video starts playing. This is useful if you want to link to a specific part in the linked video that is relevant to a point being made on the playing video. You can also choose to have the linked video open in a new window.
Should you wish to delete the annotation, you can delete it by clicking the dustbin.
You can add more than one link in this manner to a video. For example, if the video is one in a series, you could, at the beginning of the video, have a note linking to the previous video and at the end, have a note linking to the next video.