Some Democrats questioned whether it was wise to give Seals a third shot, when he couldn't beat Kirk in two thoroughly Democratic years ('06 and '08). The other way to look at it is that it was the moderate Kirk who won those campaigns, not the GOP, and with him gone, Seals has a much higher name recognition than the newbie Dold.
Whatever the case, Dold needs to get his name out there quickly, and that's where web videos come in:
Another wrinkle in this race is the attention the parties' congressional committees are giving it. The DCCC just announced that Seals is part of the "Red to Blue" program, which highlights just 13 races throughout the country worthy of special notice to donors. Meanwhile, the NRCC has Dold as one of its Young Guns, which basically does the same thing. (Also on the NRCC's Young Gun program are Adam Kinzinger (11th) and Randy Hultgren (14th).