@JudyY this is a great question and you can find many different answers here on the forum. Click on the spyglass at the top of the page and type in something like “sitter questions during video chat” and you can find lots of valuable info or click Sitters Need a Phone/Video Call Before we are Booked! - Owner & Sitter Exchange - TrustedHousesitters Community Forum where you will see this topic discussed.
I feel a two way conversation filled with questions and answers in necessary to make sure you know what to expect. My most important questions were always about elaborating on a statement in the profile about feeding, walking, meds, etc., so there are no surprises.
Good luck!