Between now and the end of July, your best chance of catching pikeminnows in the Lower Fraser River is by using bait. Water visibility is zero regardless where you go in this system. Dew worm, dough balls, salmon eggs, krill, shrimp all work well. You are unlikely to encounter cutthroat trout, but you might bump into the odd bull trout if you are using salmon eggs. These have to be released with care like all wild trout and char. Pikeminnows caught during this time of the year in the Fraser are actually not that big. You are more likely to encounter big ones in August and September.
The video on spincasting for pikeminnow was filmed in September, when water clarity is quite good. That type of fishing does not really start until the first or second week of August, when freshet starts tapering off.
There are a few places in the Fraser Valley where you are more likely to catch bigger pikeminnow right now. Cultus Lake in Chilliwack, Harrison River around Kilby Beach, Stave River are all excellent spots. The water is clear, the fish are actively feeding and the scenery is better.