Depending on the size of your site I would think from a usability standpoint that may be confusing, but you could implement breadcrumbs to remedy the confusion.
From an SEO point of view, I would think that it would be a lot easier for Google to see the differences between two products. For instance, if you have two products DX600 and NX600...
/cameras/point-and-shoot/sony/DX600
/cameras/point-and-shoot/nikon/NX600
would be pretty easy for a crawler and/or user to figure out what the page is about.
If it were just /DX600 and /NX600 that might be a little more complex for users and crawlers - is it a camera, computer, coffee maker, napkin dispenser???
And depending on your site, CMS, and industry, you may have to get creative with your URLs so you do not create duplicates and it may even be difficult to manage if you do not know exactly where to find a page is that you need to edit.
That is just my personal opinion on the subject. I would be interested in viewing the webinar you are talking about - if you have time, please post a link.
Again, I am not saying this is a bad idea by any means, but I think it definitely could make for some interesting issues if not planned out well beforehand.
Mike