If you remove the watch?v= and replace with embed/, you’ll get a link that goes directly to the video without the rest of the YouTube site—and it’ll play full-width in your browser. So, for example, you would take this link:
$$
youtube.com/watch?v=o5GDrJEGkVk
$$
and change it to this:
$$
youtube.com/embed/o5GDrJEGkVk
$$
And you won’t have to log in. Alternatively, you can add nsfw before the youtube.com portion of the link:
$$
nsfwyoutube.com/watch?v=o5GDrJEGkVk
$$
This will take you to a different site to play the video (and subject you to some ads), but it’s a bit faster to type in. You can accomplish much the same thing by typing repeat into the same spot in the browser bar instead, as follows:
$$
http://repeatyoutube.com/watch?v=o5GDrJEGkVk
$$
