On Surftourist.com we've had some people putting in a vimeo or youtube link in their descriptions. We want to support video properly, but this is a quick attempt at addressing the solution for the meantime.

embed_videos.coffee

# Search for video urls within an element and embed them if possible
embedVideos = (el) ->
  el = $ el
  if el.length
    el.each ->
      section = $ @
      matches = section.html().match /http:\/\/(www\.)?(youtube|vimeo)\.com\/[^\s<]*/gmi
      if matches?.length
        # Vimeo or Youtube?
        for match in matches
          # Use embedly for youtube because youtube oembed doesn't support jsonp
          # Don't use embedly for Vimeo because it's slower than vimeo
          $.ajax
            url: "http://#{if /youtube/i.test(match) then "api.embed.ly/1/oembed" else "vimeo.com/api/oembed.json"}?url=#{encodeURIComponent(match)}"
            dataType: 'jsonp'
            data:
              format: 'json'
              iframe: 1
              maxheight: 300
            crossDomain: true
            success: (data) -> section.html section.html().replace(match, data.html) if data?.html?.length