VideoAd carries the price before anything is rendered, so you can compare it with other networks and decide:
price.value is a CPM in price.currency. price.precision says whether it is a DSP’s clearing price (EXACT) or a forecast for house demand (ESTIMATED).
reject tells the server at once, and the server tells the advertiser its win produced no impression. Use Outbid when another network won on price, with the winning price and the network, so we can optimize our bids for your traffic; NotUsed (the default) for any other reason: the moment passed, the viewer left. Rejecting is optional; an ad you never use is settled when it expires or when you call destroy().