I have both. We used video monitor when both we very small.
For first baby we used video only. Every time we heard noise we wanted to go in and take a look, but with the monitor you see everything so no need to go in. With second one we still used video but not as worried about all the noises.
We still use both but only as audio monitors as keep one at home one at ILs. The video is exp but I dont't regret buying it as it was extremely handy when they were small.
Honestly you really dont't need the video monitor; but I found it reassuring to know they were OK. Also when they got a bit older and would wake at night we just had to look at video to see what they were doing.