I found a bunch of videos of people doing kechari and it appears most of them have never even heard that word "kechari" they just think they are swallowing their tongues! here is a few of the links...
I'd say it's a great difference between what they are doing in those links, Thokar. The first two links I'd say they are really swallowing their tounge. The third video and the last video shows kechari, when you take the tounge up instead of down. (The fourth was to blurry - I did not even see what the two young kids did.)