I also (in the continuing attempt to fiddle with this screencast thing) recorded a video!
An interesting observation that I felt like reproducing here:
Q: What does it mean to "work out your salvation"?
A: This is a tricky one, especially in light of God's sovereignty highlighted in v.13, as well as earlier in Phil. 1:6. I think the answer is that Paul is recalling back what he wrote in Philippians 1:27-28
27 Only let your manner of life be worthy  of the gospel of Christ, so that whether I come and see you or am absent, I may hear of you that you are standing firm in one spirit, with one mind striving side by side for the faith of the gospel, 28 and not frightened in anything by your opponents. This is a clear sign to them of their destruction, but of your salvation, and that from God.
In that passage, their unity in the Gospel and fearless Christ-like living is a sign of their salvation. In the same way for this passage, continue to work out this salvation through living a manner worthy of the Gospel.
Another tie is the remark "whther I come and see you or am absent," which seems to parallel, "not only in my presence, but much more in my absence"