The flowplayer3_playlist has its own options for width/height (flow_player3_playlistheight and fllow_player3_playlisthwidth).
Note also that the playlist layout - playlist entries and the scrolling etc – itself is also depended on CSS (and jQuery) . So you might have to change the css if you change width options, too. you can have theme specific playlist css, see the documentation of the plugin.
If you want just specific albums to use the playlist you will have to setup your theme as describe, best using an "album theme" (see the glossary on our site for info)