Fix handling of frame-level vs. video-level features in the commands given in the readme.
Fix handling of frame-level vs. video-level features in the commands
given in the readme.

google/youtube-8m,mwoodson1/youtube-8m-competition,lidalei/youtube-8m,hxkk/u8m_test,KangHsi/youtube-8m,slai11/youtube-8m,coded5282/youtube-8m,forwchen/yt8m,KangHsi/youtube-8m,slai11/youtube-8m,slai11/youtube-8m,slai11/youtube-8m,forwchen/yt8m