The secret is in the special sticky adhesive strip (they come already attached when you purchase them and most brands provide an extra strip of glue for reuse...more about that in the video). It's super comfy and flexible enough that you have as many tries as you need to apply them perfectly straight - and they still stay on all night. Just give the edges a little extra squeeze and you're good to go.
A few things I forgot to mention in the video:
Try to avoid using tweezers or any other "tool" to wedge the lash strip into your natural lash line. Although this is my usual method, I discovered metal and plastic stick to the glue strip and can pull the falsies right off. I just use my fingers and it works great.
There aren't a lot of varieties to choose from. So if you're not all that crazy about the few that Revlon and Eylure offer, you may be out of luck. However, the Revlon "Intensifying" set suits my tastes perfectly. They give just enough added length and volume without looking costume-y.
I think that about covers it. So sit back, relax and enjoy the tutorial!