WASHINGTON (Reuters) - A top official at the U.S. Internal Revenue Service on Thursday acknowledged that it was "embarrassing" how much the tax agency spent on training videos, including a Star Trek spoof, and other lavish expenses during a 2010 conference in California. Faris Fink, commissioner of the agency's small business and self-employed division, told lawmakers the videos, which cost more than $50,000 to produce, were well-intentioned but in hindsight inappropriate. "It's embarrassing. I apologize," said Fink, who played the character Spock in the Star Trek parody that included a tax-themed skit. "I regret the fact that they were made."...