Traditionally the way a developer handles this is they have an event that is triggered by some action, such as on slide change, where it finds the iframe for the video player then copies the contents of the "src" attribute into a benign attribute such as "original\_src" and then changes the contents of src to either empty or an image of some sort.
A few years ago, on at least two Drupal 8 websites, we noticed problems where the page/site cache is not automatically clearing when new content is added. This then requires a manual clearing of the varnish cache to show updated content.
Today my EmbedIt.in Integrator module for Drupal 6 reached full project status. It is the first project that I have submitted to the Drupal community. I have already tagged version 1.0 for Drupal 6. I hope to soon have a version for Drupal 7 available.
Today I submitted a contribution to the open source e-commerce project called OpenCart. My contribution is an XML product feed generator script that is compatible with Google Base. It requires no modification of the Open Cart core and is a simple upload installation.