These are accessible & enjoyable. I am on lecture 12 and learning a lot. Warning: some topics, such as sorting on a machine with unrealistically huge word size, are of only theoretical interest (but it's great theory).

Which to you recommend as most practical to learn, for folks on short time budget?

Geometric, lectures 3 and 4; helps (at least for me) to have a picture of the problem as a guide

The ones on memory hierarchy (cache oblivious algos, etc)

Erik Demaine is a genius, if I am not wrong he is probably the youngest to join as a professor in MIT. I think he was 21 when he joined.

Do these advanced data structures remain only in the academic world or do they get a chance to come out in the real world?

Having watched some other MIT lecture sequences, I'm really looking forward to this.

Data structures are one thing I believe every software engineer should have a solid foundation in, and it looks like these lectures will provide a nice additional resource.

By far the best model of distributing a course online

I agree and encourage anyone who has ummed and ahhed about viewing lectures online to check these out to see just how accessibly and watchably it's being done. e.g. Clear video with good audio and auto-page-turned lecture notes on the right.

Back in my day (2008) we had nothing like this, and that was at a top 5 UK Math(s) University.

See the corporate sponsorship banner at the bottom, on an MIT course website? Fascinating.

Edit: it is actually a Danish nationally funded research lab.