I was in a party with my friend (he was party leader) and he initiated the cutscene/speech in Khor Valar with Vigo.
My friend saw/heard everything but for me Vigo disapeared at that moment and I could not talk to him or hear anything he said.
After his speech Vigo followed me and I got the next Mission as normal, like my friend.
Same. Happened in Kor Valar and it happened after we traveled carrying “the item” around. (Both times Vigo. First time I did not get the cut scene, second time my friends did not get the cut scene. When I had it Vigo was gone and the quest remained in its state until the videos lasted for my friends.)
At least we could continue and the state of the main quest (line) looked OK when we left the party.