This is a lecture by Dr. Peter J. Williams titled “New Evidences the Gospels Were Based on Eyewitness Accounts.” (There’s also some good evidence for why the non-canonical gospels were not.) Dr. Williams has an engaging style, and the information is fascinating, so it’s well worth your time. The lecture was given a couple of years ago, so the evidences are not as new today, but I’ve found that the information is still not as widely known as it should be.
You can view the Q&A portion of the lecture here.