Always add youtube clips to watch later list
I guess the easiest way is using an app like Pocket (formerly known as "Read it Later"). Pocket accepts input from all kind of apps via the "share" menu; I e.g. use it with my RSS reader, Twitter apps, Browser, and more. So far for the "Android end": Even before the buffer starts filling, press "Share", select "Pocket", done.

Now for your PC, Pocket offers addon for several browsers. For me, that's Firefox, and it's addon works like a charm: I've got a small icon next to my URL bar, which opens a (paged) list of saved entries which even offers a search/filter function – so it's easy to pick the wanted entry (here: Youtube URL) and watch the movie.

The "share process" on your Android device works in the background (gives you status information via "toast messages"), so it doesn't disturb you in whatever you're doing. As a side effect (you might already have taken that from my above description) you can do the same with a lot of other stuff you want to "consume later" – as long as it provides an URL: Tweets, web pages, RSS feeds, probably also Podcasts and more. And if you decide to check some of the stuff while on the road, Pocket offers a reader for that as well (included with the app).