The most useful gauge is the Beaufort sea state descriptions. Although waves look flatter on video, the appearance of white caps, flying spray, etc., still shows up.
On many of these 30 knot videos, you see scattered whitecaps, indicating maybe Force 4 - wind in the mid to upper teens.
When wind is Force 7, in the low 30s, you should see "Seas heap up, white foam starts to blow in streaks along direction of wind, spindrift forms"
I suspect most of the 30 knot YouTube sailors would be safely home (as they should be), or heading home, after soiling their pants, in such conditions.
It is common to see 3 - 4 foot chop in the lower Chesapeake Bay, where there is much greater fetch over which waves can form: