While the original "kings" have mostly been dethroned by legal challenges and updated YouTube policies, you can still achieve the "3gp king youtube full" experience today for archival or nostalgic purposes. Here’s the modern method:

At its core, the site serves as a digital entertainment hub, offering everything from music videos to full-length movies compressed for mobile playback. Why People Still Download YouTube Videos in 3GP

It sounds like you're looking for a social media or forum post related to the nostalgic term — likely referring to old YouTube videos (often Bollywood songs, funny clips, or movie scenes) that were uploaded in the low-resolution .3gp format back in the late 2000s and early 2010s.