Was Paul an Eyewitness of Jesus' Resurrection?

In a recent response to Wes Huff, Bart said the only eyewitness we know of who's converting people is Paul. A lot of people pointed out that Paul never met Jesus.
Fair. But Paul is also the only person in the New Testament who tells us, in his own words, that he saw Jesus alive after his death. Everyone else reaches us secondhand.
Bart unpacks what Paul actually claims to have seen, why Paul is the only person who claims to see a resurrected Jesus, and why the earliest firsthand evidence for the resurrection suggests visions.