I don't have much to say about the Special Tribunal of Lebanon. There certainly was a well organized assassination of Rafik Hariri on February 14, 2005. The United States would certainly be happy for the aftermath of the assassination to harm the interests of the US' adversaries such as Syria and Hezbollah.
It was immediately clear to me when I first heard the news of the bombing that Israel would consider it a good thing, that the scale of it would trigger an anti-Syrian backlash while Hariri, who at the time was not an active politician, would not directly be a major loss for anti-Syrian factions in Lebanese politics.
If I had to guess who was responsible for the attack I'd say Israel, just because that is the only party that might have thought it could benefit from the attack at the time. But it would not be a particularly informed guess.
The important question for Lebanon is how credible is the tribunal itself seen by Lebanese. The indications I've seen are that it is not very credible. Saad Hariri was forced from power because he refused to put cooperation with the tribunal to a vote in his own cabinet - which at the time was dominated by his allies. That is an indication that the local consensus is aligned with Hezbollah's accusations that the tribunal is less a tool for justice than a tool to harass the US and Israel's adversaries in the country.
Nasrallah's overall message is that the indictments change nothing. Interestingly Nasrallah explicitly shields Lebanon's Prime Minister Mikati from responsibility for any failure by Lebanon's government to cooperate with the tribunal by arresting any indicted Hezbollah personnel.
As for the March 14 camp, Sayyed Nasrallah addressed them saying "you consider yourself as the opposition and this is your right. But I have two pieces of advice for you: First is that you should not hold the cabinet of Prime Minister Najib Mikati responsible for not being able to carry out the arrest warrants (of the STL's prosecutor's office), which the Hariri cabinet would not have had been responsible for either at the time. Even if the cabinet was backed by March 14, it will not be able to carry out the warrants and arrest the indicted people. I don't think that they will be able to arrest them not in one, two or even in 600 years.' As for the second piece of advice to the March 14 parties, Sayyed Nasrallah said "Do not ask PM Mikati or his cabinet to give up his goals in order to remain in power, just like former PM Saad Hariri did."Other than that, all parties are acting exactly as we'd expect them to.