I was following cyb's A/B just now, after basifying, I recall shaking the flask very violently, and now I'm stuck with this foam layer, please help.

A bunch of things you can try:
1) Wait
2) Warm it up a bit
3) Agitate with gentle vibration
4) Add a bit more lye

Had the exact same problem with Cyb's teks. Add a spoonful of lye and heat it up, shake, and settle. I've also tried adding some extra salt, which doesn't seem to hurt. That should help a lot. Repeat if necessary until you're happy with how much naphtha you can get.

Agitation did not seem to help in my case. YMMV.

And in worst case scenario you can suck it up with a Turkey baster and poor the top layer into another bottle and add more water and it will separate eventually. Thus you can still continue working with the original vessel.