The sentence "Ad Manager will compare the bids of all sellers and the best contextual ad selected via dynamic allocation" could be interpreted in two ways
1) Ad Manager will compare the bids of all sellers and the best contextual ad (which is selected via dynamic allocation).
2) Ad Manager will compare, via dynamic allocation, the bids of all sellers and the best contextual ad selected.
The intended meaning here is (1), and this edit makes that clearer.
The sentence "Ad Manager will compare the bids of all sellers and the best contextual ad selected via dynamic allocation" could be interpreted in two ways
1) Ad Manager will compare the bids of all sellers and the best contextual ad (which is selected via dynamic allocation). 2) Ad Manager will compare, via dynamic allocation, the bids of all sellers and the best contextual ad selected.
The intended meaning here is (1), and this edit makes that clearer.