Bearing in mind that I know nothing about this, it seems as if the following is true. 1) The fact that you've 30 mbps download doesn't tell you anything about how fast upload will be. 2) Upload through wi-fi in Thailand generally, and in Isaan in particular, is likely to be slow.

The time difference between the West and Thailand made me think that a politics vlog might be workable - you've a competitive advantage because the day's news stories are going live in the papers when you get up in the morning - but am I right in thinking that a DTAC dongle, or something similar, would be needed?

Upload speed and download speed are two separate things. Upload is significantly slower than download speed. Check your package, it should be stated there what up and down speeds are.

2) Upload through wi-fi in Thailand generally, and in Isaan in particular, is likely to be slow.

Neither nor.

Believe me there is no slowdown because you are in Isan

It depends on your connection and package.

All individual.

In former times the download/upload ratio in Thailand was quite high like 10/1.

I have 30 / 3 and uploading to youtube or MEGA was usually steady at about 2.6.

This ratio is/was indeed different from what is offered in most western countries and the low upload rate supports your argument.

Nowadays they offer more and more "symmetric" packages llke 25/10. 50/10 etc.

I assume you are somewhat experienced to usefully prepare a video before upload.

Best always use a converter to desired youtube format (360, 480, 720, 1080) before uploading.

Think twice what resolution is really needed.

Full HD 1080p will of course blow up sizes and times to huge numbers.

(just found a trivial smartphone video of a new years party, 135 MB for 1:06 min )

Do not try to upload a 30 min video with 18 GByte (!) directly from an "action cam" like some Bangkok poster in a German forum did.

The readers had to wait overnight.

youtube shrunk the stuff to about 200 MB or so

What a waste of bandwidth.