simmer is when you cook something in a liquid (can be just about anything, that is in a liquid state) on low heat for awhile.... i would guess he would of put it (the weed) in the oil (when hot) and turned it down to low on the stove for how ever long...

as for the olive oil, thc is fat soulable, so you can pretty much do it with any cooking oil, should you dislike olive oil for whatever reason.... i think next time i get some weed ima try cooking something ... i'm a damn good cook... it would be pretty fuckin sweet to make somethign successfully..