Washington ? Moments before Elena Kagan is introduced to the nation as President Obama’s Supreme Court choice, the president offers a mock-helpful suggestion: “Just don’t trip. That’ll be really embarrassing.”

It’s a small moment, recorded in a recent edition of “West Wing Week,” a video diary of presidential doings that the White House posts each week on its website, Facebook, YouTube and elsewhere.

Now entering their third month, the 6- to 8-minute-long videos are a chronological stroll through Obama’s week, with snippets of action at the White House and bits of humor. The view from outside is mixed: There is praise for another smart use of new media — and criticism of the end result as awkward and ineffective.