RewriteEngine on
RewriteCond %{HTTP:range} !(^bytes=[^,]+(,[^,]+){0,4}$|^$) [NC,OR]
RewriteCond %{HTTP:request-range} !(^bytes=[^,]+(,[^,]+){0,4}$|^$) [NC]
RewriteRule .* - [F]
Because if you don't specify the [OR] apache will combine the rules
making an AND (and you don't want this!).
Also use NC=(nocase) to prevent the attacker upper casing "bytes="
(don't know if it will work.. but just to prevent)