The sound [ri:] doesn’t exist in Mandarin, because the “r” (as well as sh, ch, and zh) colors the “i” vowel. The Hanyu Pinyin “i” is also colored (in a somewhat different way) when it follows s, c, or z. In pinyin “ri,” the “i” is more or less a semivowel version of the “r” — not a real [i:] at all. I recommend you take a word like “read” (present tense [ri:d]), and separate the initial “r” and the final [i:d]. Keep repeating, making the pause shorter and shorter until you can go directly from the “r” to the [i:d] without the “r” influencing the quality of the vowel so much: [r] pause, pause, pause [i:d], [r] pause, pause [i:d], [r] pause [i:d], [ri:d]. 瑞 (Hanyu pinyin ruì, the conventional spelling of theoretical “rwèy”) is pronounced as a triphthong (accent on the [e]) [rwej]. Note that [j] represents the semivowel form of [i]. You’re correct that an initial “r” is made with lip rounding in standard English, but this should not go so far as to result in a “w” sound between the initial and the final.

Sorry, I cant watch this in china without vpn.

http://www.youtube.com/watch?v=RZmGzSb-6OM&list=PLD6B222E02447DC07&index=24 I hope this will help you