(This is the Warren Buffett Watch newsletter, news and analysis on all things Warren Buffett and Berkshire Hathaway. You can sign up here to receive it every Friday evening in your inbox.) NetJets says it will not speculate on what caused one of its planes to crash onto a highway in Laredo, Texas late Tuesday, killing a prominent tech entrepreneur. Joshua Baer was the 50-year-old founder of Capital Factory , a VC company in Austin that specializes in tech startups. NetJets did say in a