Firstly, prepare the place for the call. A quiet environment is a must-have. Pay attention to what the interviewer will see in the background (sometimes when I do coaching via Skype with you I can see really strange stuff;) Prepare on the wall in front of you the material you might need (structures, tips for a fit part, etc) so you won't have to look for it during the interview
Prepare your own questions. Relevant questions at the end are a great way to show your interest in the company and get additional points. This is particularly important in a phone/video interview, as the interviewer will naturally connect less with you.
Smile during the call. Even if they cannot see you it's a good way to show energy
Use numbers when communicating your structure. This applies to both face-to-face and video interviews, but it is particularly important for the video ones. Good communication will make it easier for the interviewer to follow you since he/she cannot see you. As an example: “In order to help our client, I would like to focus on three main areas. First, I would like to focus on [FIRST TOPIC], secondly on [SECOND TOPIC], finally on [THIRD TOPIC]. Let me start with the first one."
Hope this helps and speak soon,