Well if you can't use this in an English lesson, then all hope is lost for the world.
Sivu - Better Man Than He. from Adam Powell on Vimeo.
Sivu's video is my new favourite pronunciation video. It uses footage that would have been impossible to collect 25 years ago. MRI and digital video. I'll have to thank Claire Fitzgerald at DCU Language Services for it. It's a great way to start the conversation about how our mouth works.
I'd suggest using it straight away to ask students about the parts of the mouth that move and ask how we make our /l/.
Maybe before showing the video have learners fold a piece of paper in half and draw what they think the mouth looks like from this split-head perspective. Do this before they watch the video and after you've used it, perhaps at the very end of the lesson or for homework, ask them to draw the same view on the other half including more detail.
As a teacher and a learner it's always nice to make the progress obvious and visual and to buck the trend and make the progress non-numeric. No one knows it all about how the mouth works, but this page will be an artifact which proves some progress in learning about how our mouth works to produce speech.
"What a piece of work is man..."