Hi Beverly,

I have listened several times but didn't hear monter being used, but did hear sortir.

Both of these verbs can take either avoir or être depending upon the usage with a direct object or an indirect object.

The two neighbours meet by chance as they are putting out for collection their waste bins. In the perfect, we can say " j'ai sorti les poubelles where les poubelles are the direct object therefore avoir as the auxiliary.

Not sure if this helps you or not?

Jim