It would appear that the technology had been taken out of Mr. Klein's hands within about a year after that video was made (2006), so perhaps his demise was deemed unnecessary by the archons involved.

http://fuel-efficient-vehicles.org/energy-news/?page_id=96

The most recent holding company for the technology appears to be Hydrogen Technology Applications, Inc.:

http://www.hytechapps.com/

Their "recent updates" do not extend beyond 2009. However there is a press release dated Feb. 2012 which indicates a joint venture named PURE AQUYGEN being formed with a Panamanian company called Pure Tech Ventures, SA. The press release contains two web addresses for Pure Tech Ventures which apparently do not work:

Pure‐Tech_Ventures.com
www.PureTechVentures.co.cr

The first is actually not a valid domain format as it contains an underline character. There is a website at http://www.puretechventures.com/, but that appears to be an unrelated health tech company. I could not find any web presence for PURE AQUYGEN.

The hytechapps.com site lists three US patents of Mr. Klein's, but I have been unable to find any indication in the patents of how over-unity is achieved in the electrolysis and combustion process. Perhaps there is an undisclosed detail in the actual device, such as application of ultrasound to the electrolysis chamber, or use of high frequency RF across the electrolysis plates, either of which might entrain zero-point energy to assist the electrolysis, but I can find no indication of this in the patents. Of course, the alternative exists that this particular water-power system may indeed be a hoax as many have asserted.

Links to PDFs of the three patents follow. A "Captcha" must be typed in to access the PDFs:

US Patent 6,689,259:
http://worldwide.espacenet.com/espacenetDocument.pdf?ND=4&flavour=trueFull&locale=en_EP&FT=D&date=20040210&CC=US&NR=6689259B1&KC=B1&popup=true

US Patent 6,866,756:
http://worldwide.espacenet.com/espacenetDocument.pdf?ND=5&flavour=trueFull&locale=en_EP&FT=D&date=20050315&CC=US&NR=6866756B2&KC=B2&popup=true

US Patent 7,191,737:
http://worldwide.espacenet.com/espacenetDocument.pdf?ND=5&flavour=trueFull&locale=en_EP&FT=D&date=20070320&CC=US&NR=7191737B2&KC=B2&popup=true