I'm... glad you asked this question. English has a strange way of taking words from other languages and punching them into shape. As with every last rule in English, there are exceptions and special cases to pronouncing French words in English.
Most of it (or so I believe) boils down to convenience. People prefer 'Parriss' instead of 'Parree' simply because the spelling has an 's' on the end, while they will happily not pronounce the 't' in 'ballet'. The only way I can attempt to shed some light on this is to go through every example you've set.
'Renaissance' is its own word in English with its own definition. In this case, you would pronounce it in an English way. Or, for someone who enjoys French, no one would mind a French pronunciation as long as it was accompanied by a heavy English accent.
'Deja vu' is a phrase we stole. 'Deja' isn't in a standard English dictionary, and neither is 'vu'. Thus, you would pronounce it as a Frenchman. 'Par excellence' is also a phrase, so a French feel is the best way to approach it.
History is slightly more difficult. I am no expert, so I'd recommend asking another teacher / historian etc for specific words. I can say with confidence though that 'Versailles' is pronounced in a very French way, as it would sound nasty in an English accent.
'Les Miserables' is part of the culture of Britannia. Everyone is aware of it. And, in English pronunciation, 'miserables' is hardly a fitting name for a show of such majesty (or so its media frenzy would suggest). Whenever culture (film, plays, books, people) is involved, chances are the pronunciation is French.
So... how to make this general. A big challenge for me. I would say: names, cultural references, words that would sound horrible in English, and phrases keep their native pronunciation; places, words we have adopted, and words that would be difficult to pronounce use English pronunciation.
There appear to be two separate questions:
- Which one is correct?
- How can I distinguish between them?
Both pronunciations are correct, but they each represent a different accent. The American pronunciation is /tʃɹ/, as in the first video. The second video features an Australian speaker, thus the pure /tr/ sound.
Assuming you are not a native speaker of English, it seems silly to provide a phonetic analysis of the two pronunciations. My recommendation is to practice the words exactly as taught in the videos. I think they both do a good job, but you need to choose the specific accent you wish to acquire and practice with that video ONLY.
The American accent video does a very good job of teaching awareness of the feel of your lips and tongue so that you include the /ɹ/ sound after the /tʃ/ sound. Here is a bookmark of that portion of the video.
Good luck!
Best Answer
The letter 'J' usually represents the sound /ʒ/ in French. In English this sound is most often represented by the letter 'S'. A large number of the words that have this sound in actually came to us from Old French. Many of them end in -sure. Here are some examples:
There are also many nouns originally from Latin which came to us from old French which end in sion. These endings are pronounced /ʒn/. Here are some examples of these:
There are also two adjectives ending -sual which usually have the /ʒ/ sound; casual and visual.
Lastly there are many words from ancient Greek with the ending -sia, often pronounced /ʒə/. Here are some examples of some of these:
The /ʒ/ sound is actually the rarest consonant sound in English. It nearly always occurs in the middle of a word. There is only one common noun in English ( - so I was told at university) which begins with the sound /ʒ/. This is the word /ʒɒnrə/, "genre".
Hope this is helpful!