Template documentation(for the above template, sometimes hidden or invisible)
Notes Because of the order in which the template and the extension are processed, the will not function unless the template is always substituted.
If you wish to always display videos at a larger or smaller size, edit the template (on your wiki) to alter the default width and height in the youtube extension code. You must also alter the width code (style="width:256px;") in the first line of the template to equal the default width plus 6 pixels, to allow for the padding specified in the stylesheet.
The maximum size is 425x350 pixels. For best results, the height should be about 4/5 (80%) of the width. Some examples of good ratios include 125x100, 200x160, and 250x200.