The filibuster, i.e. an extra-constitutional obstructionist tactic - speaking about irrelevant things for hours in the Senate, trying to delay a decision, has been used by both parties throughout the U.S. history. In the 1950s and the 1960s, it was used to prevent new bills about the civil rights.
Recently, at least 10 conservative judicial nominees have been filibustered by the Democrats in the Senate - an unprecendented large number. Princeton's alumnus, the Senate majority leader William Frist, proposed the "nuclear option" based on the paradigm that it should be enough to debate a candidate for 100 hours - and a vote should follow afterwards. Today it takes 60 votes to stop a meaningless debate; according to Frist's new rules, it would take simply 51 votes in the case of judicial nominees.
Most Democrats and other left-wing forces - which also includes 95 percent of intellectually diverse Princeton University - vehemently disagree. Everyone should be allowed to speak for hundreds of hours and maybe for years. It is vital for democracy to obstruct and delay nominees that the correct people do not like - much like it is important for bureaucrats to slow everything down as much as possible (these slowing procedures are usually extremely efficient and in many cases more annoying than a "no" vote). For example, it is important to read random pages from Introduction to Elementary Particles by David Griffiths for more than 50 hours.
Edward Witten and Chiara Nappi are not the only ones - Frank Wilczek is having a great filibustering time in Princeton, too. ;-) See also the filibuster webcam and program in Princeton. I was explained that the last sentence was "unnecessary".