I must have patched a hundred tires when I lived in the desert. I noticed this guy trimmed the plug too soon. You need to run in on the road to fully seal then trim.

Went to tire store to get one tire plugged. They wanted to sell me a new tire.. I sent to automotive parts store next door. Bought a plug key for 4 bucks and did it myself. Tire still up and going for over a month now. Will not buy any more tires at that tire store now.