Thorough, thought, cough, furlough... Why so many ways of pronouncing OUGH in English?

Why are there so many ways of saying "ough" in English? Watch this video and you'll understand.

===OUGH SO MYSTERIOUS===
The inconsistent pronunciation of "ough" is perhaps the best demonstration of the madness of English spelling. Well, ENOUGH is enough. In this video, I PLOUGH THROUGH a THOROUGH history of the problem. By the end of it (barring any HICCOUGHS) you’ll have a ROUGH understanding of why English spelling can be so TOUGH.

You'll also know how to pronounce LOUGHBOROUGH - the place name that has baffled many a visitor to England.

===NOTE FOR ENGLISH LEARNERS===
If you want to know how to say words containing ough, this video includes a handy pronunciation guide for: bough, bought, borough, brought, chough, dough, enough, fought, furlough, nought, rough, slough, sought, through, tough, trough and wrought.

===CHAPTERS===
0:00 The Problem
0:47 The many ways of saying "ough"
1:13 Reason 1: The Great Vowel Shift
2:38 Reason 2: Extinct pronunciations
3:10 Reason 3: Folk etymology - hiccough
3:58 Loughborough
4:23 How to pronounce ough words
5:24 Thanks for watching