The iPhone cannot view Flash content. Steve Jobs has recently hinted that Flash support is not coming any time soon as he thinks the standard version is too processor intensive for the iPhone and the mobile edition is too under-powered. It would appear that Adobe would have to create a version of Flash specifically tailored for the iPhone for Apple to consider including it.
bmrumble is correct. The iPhone can only take so much, so yes, Adobe would have to create one specific version of Flash for the phone. Until they do, you’re going to have to watch YouTube and other Quicktime format videos on the web. I have yet to find much of any Quicktime vids on the net worth watching.