I haven't even looked at Netflix. They are a sore spot for me and I have to say that they've really screwed their site up on numerous occasions. The management of NF even asked for free help from the webdev public community at one time in a blog. They insinuated that they just didn't have the resources to improve their site like they would like to, and they actually, in so many words, asked thier customer base to help them by coding improvements and apps.
I would imagine they use some convoluted jquery/dbase system. There's an easier way.
Here's where to start:
http://www.wickham43.net/hoverpopups.php
If you have variables that will dictate what information and links you need to have in your hoverpopups, you'll need a dbase and you'll need to incorporate a query and some PHP script to populate your hoverpopups with the correct information. Being that your example was basically a need for "help balloons", if it's not all that complicated and you don't have a bunch of variables that dictate exactly what info you need to appear in the hoverpopups, you can use includes within the span. Many thanks to Wickham. I've done some amazing things with these hoverpopups. If you have them "touching" the "original" div, you'll have (cursor) connectivity and you'll be able to have appropriate links in the hoverpopups (the spans). Since they no JS is involved, they are SEO, engine, and bot friendly.