first, anti china feeling exists since the dinosaur time, not since northvietnam took over southvietnam. PRC stopped all supports to northvietnam since 1968 and started hostile actions including military means to punish vietnam. why? because northvietnam signed military alliance with USSR.
second, the hoa enjoy all freedoms in vietnam. of course, including watching chinese movies and dramas.
last, if any Hoa thinks vietnam is poor and backward, while china is great and rich, he/she can leave. despite all anti china feeling, we give them foods, shelter and home when they need us. if anyone feels we are inferior to chinese race, we won´t stop them to go.