Visible crew/equipment: When Angel is fighting the worm demon you can see a cameraman in one of the shots. (00:27:05)
Visible crew/equipment: When Angel is fighting the demon, you can see an obvious camera and two hands in the bottom right corner. (00:27:10)
Visible crew/equipment: When Angel is fighting the demon a cameraman is visible rising on the lower right. (00:27:13)
Visible crew/equipment: When Angel kneels down to the fridge a camera lens is visible in the top left. (00:15:21)
Visible crew/equipment: When Angel is drop kicked to the floor a camera LCD in the lower right is visible. (00:24:35)
Visible crew/equipment: In the scene where Angel is talking to Kate about the "evil thing" , the boom mike appears at the top of the frame. (Widescreen Edition).
Visible crew/equipment: At the end of the episode where Wesley is studying the Shanshu scroll in Cordillia's apartment, the boom mike appears at the top of the frame TWICE.
Answer: Everybody including Angel saw her. After helping them and then being left alone to talk to Angel, Cordelia says that the Powers That Be let her come back one more time to help them. After Angel gets a call saying that she died, he realises that it was her spirit that was helping them the entire time.