Your patent FUD: any software can be potentially sued for patent infringement. You can't prove the opposite. See Oracle vs. Google on Java patents and a number of other examples.
Pointing that out about WebM software specifically is not insightful. You can make the exact "but can you prove it doesn't infringe patents" statements about any software product.
There are, however, reasons to believe that WebM does indeed avoids patents.
1. It's a technology that has been created and commercially licensed by On2 for years. In all those years no one sued On2.
2. On2 licensees (including Adobe) were confident enough about the technology being patent-free to pay good money for the license.
3. Google, presumably, is not stupid and didn't pay hundreds of millions of dollars without doing a technology evaluation, including potential patent issues.
4. Even if someone sues WebM, Google has a better chance than most to defend it.
So while no one can ever satisfy people demanding impossible proof of WebM being safe from patent threats, there are very good reasons to believe it is indeed safe.
1. On2 never went to market with VP8 before the sale to Google. To say that they weren't sued for something they didn't release doesn't prove anything, especially since VP8 was marketed as a evolution of VP6.
2. See #1, they licensed VP6 not VP8/WebM.
3. No doubt!
4. Google does not indemnify users of WebM (http://www.webmproject.org/license/software/). If someone were to sue you for WebM, it's not an attack on Google and they have no reason to pick up your legal bill. Sure, it's not unreasonable to assume that if many large companies adopt a technology it's safe to use, but it doesn't protect you from being attacked individually.
There's a difference between hardware designs and actual hardware... Google doesn't offer indemnity for use of the format so why do you think they'd be the only defendant? If Google's so smart like you say, if they're so kind hearted, then why aren't they offering indemnity?
Perhaps because the MPEG-LA does not offer indemnity, either. See the Alcatel-Lucent lawsuit against Microsoft, or the fact that WMV became more visibly patent-encumbered when Microsoft submitted it to SMPTE for certification as VC-1, to see how this sort of problem affects the "other guys," too.
Your patent FUD: any software can be potentially sued for patent infringement. You can't prove the opposite. See Oracle vs. Google on Java patents and a number of other examples.
Pointing that out about WebM software specifically is not insightful. You can make the exact "but can you prove it doesn't infringe patents" statements about any software product.
There are, however, reasons to believe that WebM does indeed avoids patents.
1. It's a technology that has been created and commercially licensed by On2 for years. In all those years no one sued On2.
2. On2 licensees (including Adobe) were confident enough about the technology being patent-free to pay good money for the license.
3. Google, presumably, is not stupid and didn't pay hundreds of millions of dollars without doing a technology evaluation, including potential patent issues.
4. Even if someone sues WebM, Google has a better chance than most to defend it.
So while no one can ever satisfy people demanding impossible proof of WebM being safe from patent threats, there are very good reasons to believe it is indeed safe.