Thanks for the response. My site consists of 3 main areas, my content, public content (mixes we found from Soundcloud etc, embed via iframe) and user submitted content (which again will use Soundcloud). I can guarantee my iframe content to stay up but the latter will need checking regularly.
If I was to discover a dead iframe I would update the post to advise that this content is no longer available. I have a disclaimer on my site to advise users that I do not own or control all the content we share.
How would I find the dead embed iframe content on my site so I can update my visitors?
[mod note - please do not bump your topic]