Some organizations may chose to conduct virtual interviews with potential employees for a couple reasons.
Some companies may be looking at candidates who do not reside close to the business. Therefore, instead of paying for the candidate to travel for the interview, the company may conduct a virtual interview. Similarly, a potential employee may not be able to travel in order to complete an interview. By conducting a virtual interview, both the company and the candidate can save money.
That said, phone interviews do not allow companies to see the candidate. By conducting a virtual interview, a company can see who they are interviewing. This allows the interviewer to watch body language and mannerisms. At the same time, "dead air" during a phone interview can be misleading. By being able to see the candidate, the interviewer can recognize if the candidate is thinking of an answer or not.