Vidyard players intelligently determine the best possible resolution for each viewer. Each time the player loads, the player thinks about all the factors that are affecting playback quality for that viewer and makes dynamic adjustments to ensure that the viewing experience is always the best it can be.
Larger files will not cause a slower streaming experience. Players will adapt to low bandwidth situations by downgrading the video resolution when a video has too much buffering. This is because most viewers would prefer to watch a lower resolution video over experiencing buffering, which interrupts playback altogether.
Please refer to these articles for more information on player loads: