If your planning a hiking trip to the Yosemite Valley in Yosemite NP here are some great highlight videos that the National Park Service has put together. They showcase and describe a few of the most popular hikes for different ability or exertion levels. They are a fantastic resource.
Watch a 4½-minute video about easy hikes in the Yosemite Valley:
Watch a 6½-minute video about moderate hikes in the Yosemite Valley:
Watch a 7½-minute video about strenuous hikes in the Yosemite Valley: