Speech synchronisation is still a little wonky, and it varies from video to video. Some of it might be manually correctable with intensive video editing but I’m not going there.
Another advantage of these short clips is that the lack of consistency with voices isn’t a problem. If I create two video clips with the same characters in them, the AIs cannot be relied upon to be consistent with the voices produced.
Grok seems much more reliable on lip-sync than Qwen, but models are constantly being upgraded so that can change quickly.