“Watch Later” Video Service for iPhone I regularly find articles on the internet and think “I’ll read that later”. These days I press a button, which uses Instapaper and lets me read it later on my iPhone. This works very well. 

However, I also often find YouTube videos and think “I’ll watch that later”. Unfortunately I don't have a handy process for easily sending videos to a ‘watch later’ on my iPhone — does such a workflow exist?
Instapaper does have some basic YouTube functionality — if you save a YouTube page to Instapaper, it will appear in the app with a thumbnail and play button, so you can play it directly there.

You might also want to check out Pocket, which is similar to Instapaper, but a bit more focused on multimedia, rather than mostly just articles. I believe it has some sort of offline viewing mode as well, but I'm not that familiar with it.