Studies from Israel and the US found that a high percentage of patients under 50 presenting to the emergency room with strokes had active or prior SARS-CoV-2 infections that they were previously unaware of.
"there was this study, multiple studies, one out of Israel and a couple out of the United States, showing that people under the age of 50 were coming into the emergency room for strokes. And one of the studies out of Israel found, because they test everyone for COVID-19, you know, a great deal of the like a high percentage of the people that were coming in for these strokes, these young people under 50, had COVID-19 and didn't even know they had had it." (said at 0:15:06)
No published record matching the claim—that studies from Israel and the United States demonstrated a high percentage of patients under age 50 presenting to the emergency department with strokes had previously unrecognized SARS-CoV-2 infections—was located; this does not prove the claim false.