This is somewhat exacerbated by the prevalence of Youtube, with its opaque URLs; something more like the approach adopted by some newspapers, with a title built into the URL, would help. (And in its defence Youtube does have a title on the page containing the video - but there's nothing to guarantee it's useful or accurate and it's not got the same kind of visual prominence as e.g. headlines on news.bbc pages, to pick another user of fairly opaque URLs.)