Just watch. :)
If you are confused about what's going on, I'll explain. In the first sections, the bacteriophage, which I'll call phage from now on, is slowly drifting towards the bacteria. It latches on and then inserts's its tail into the bacteria. It injects it's DNA and disrupts the reproduction system of the bacteria, making phages instead of more bacteria. Then, the phages withing the bacteria release an enzyme, which explodes the bacteria. That releases the phages, which go on the redo the cycle.
