Eddie Peng and Guei Lun-Mei are seen in a series of adverts/micro films with an eclectic mix of music by Grace Chang, Booker T and the MGs and Leslie Cheung. The four stories (made in 2011) are based on the themes of "Sweet", "Sour", "Spicy", and "Bitter", a follow up to the 2010 'Bittersweet" advert (seen first in the compilations), also co-starring Eddie and Lun-Mei.
The product, it turns out, is a chewing gum with the brand name 'Yida' made by Wrigley. I thought it was an antacid or some sort of digestive aid when I first watched the unsubbed version. (Source)
Compilation video (unsubbed)
Director's compilation - subbed
Yida, of course, has its own weibo, with new videos. They're a new series, "Bittersweet II", just recently released in August, I believe. It co-stars the original pair plus the addition of Andrew Lin.
The director of the 2010/2011 videos (not sure if he did the new series) is David Tsui/Tsui Pui-Hon (徐佩侃). Check out some of his other, older adverts with Anita Mui and Chow Yun-Fat (and Jacklyn Wu Chien-Lien/Ng Sin-Lin; you might have seen these classics before). And then, a modern update follows. Very sweet!
Chow Yun-Fat and Jacklyn Wu
The second video in the trilogy, shot in Furano, Hokkaido Japan and Shaw Brothers' Studio Backlot in Hong Kong.