Hi Adam

That seems like two separate questions to me:
1. Aesthetically / Graphically / Tonally / Look-and-feel-ey what is the right balance to strike between content and advertising? (no short answer - a usability and commercial question)
2. From a file size point of view, how big can Flash files be without slowing site down too much?

Which were you most interested in? Or both...?

The second question, equally, isn't really about Flash in my view, but about page weight and speed more broadly. Or, rather, site speed. And not just actual speed but 'perceived' speed by the user e.g. a design which puts all page content into a single table will only render (appear to the users) when *everything* has downloaded. Whereas a site using CSS, say, will begin to appear as it downloads. So the latter will appear 'faster' than the former even if the latter's actual size/speed is greater. Make sense...?

Some further reading on all this:
Response Time Overview - Jakob pronounces on how long people are prepared to wait...
Ten ways to speed up your site - from forum regular Mr Moss...
Download speeds etc. - some more in this thread on actual vs. perceived download speeds. 

In the end it's all about customer experience (note how up-to-date I am with the latest buzzwords...). Fast is good. Slow is bad. Permission-based and targeted is good. Interruptive is bad.  Etc. etc. 

I suspect the bigger question is "how do we sustain advertising revenues if few(er) people are clicking on the ads? Do we need to make the ads bigger, flashier, more 'attractive'?".

That's a bigger question, of course, but my short view would be:
- Yes, there is still room to improve online ad formats and quality of creativity to get better response (rich media, minimalls, AJAX, streaming etc.)
- There is an increasingly valid argument that online ads do drive sales indirectly or through other channels (so we shouldn't be selling just on clicks)
- I think it may be better in the long term to do fewer, bigger deals with advertisers (more sponsor style than banner ads by the truck load) where the advertising can be more integrated and much cleverer. And there'll be less of it meaning what is there will get a better response.

Ashley Friedlein
CEO, E-consultancy.com