This is used to create partial or complete transparency. Possible modes are copy none direct. These modes all specify no transparency, which is the default for most image formats. It accepts a second parameter, color, that specifies the color to be rendered as transparent. The color parameter may be any valid color specification supported by Cascading Style Sheets, level 2.
Legal values are true and false.
Default is false. Opening all the media elements at the beginning of the presentation can take considerable time and memory, so we recommend that it be done only for simple presentations with a few small media elements. When used in an element tag, specifies that this particular element should be downloaded or streamed as soon as the presentation is opened. You might use this to preload an element to be sure it is already in memory when it needs to play. Possible values are character strings matching a valid MIME type.