[wp-hackers] Embedded videos are not resizing

[Otto]

How embed width works:

1. The global $content_width is the default for width.

2. The settings in Settings->Media->Embeds override that for anything
using oEmbed. This means anything using the [embed] shortcode or the
auto-embeds. Same goes for height.

3. Specifying width/height in the [embed] shortcode overrides even that.

4. This only affects actual embeds, not copy-pasted code from elsewhere.

5. This isn't retroactive. Once the oembed does its magic, the actual
embed code obtained is cached in the postmeta. It won't resize just
because you change the settings again.

-Otto