In "Private Movies 18 - Girls Night Out" scene 5 (2005) a fascinated waitress watches Claudia Rossi & Veronica da Souza's erotic encounter at the bar.
In screenshots below she is to Claudia Rossi's left: (see scene 5 set)
In this clip she offers da Souza a glass dildo (on 6 minutes 22 secs) but beyond a voyeur's interest plays no active part:
She's seen behind the bar in a black cocktail dress 20 seconds into this trailer:
Can anyone ID the woman playing the waitress? Did she feature in any other movies? She's not mentioned in credits by Private.