So you have your 261 legally-converted 3GP files. What can play them?
While cinema purists argue that movies should be watched on the biggest screen possible, the mobile format has changed how stories are told. Mobile-friendly movies often feature tighter editing, dynamic subtitles, and narratives that are engaging even on a 6-inch display. 261 movies for mobile phones 3gp -links-
Searching for specific movie download lists or direct links to files is often difficult today because this format was primarily used for older "feature phones" (like early Nokia or Motorola models) and has largely been replaced by MP4. So you have your 261 legally-converted 3GP files
Based on forum archives (XDA-Developers, HowardForums, and Esato), these were the most frequently found films in those 261-movie collections: Mobile-friendly movies often feature tighter editing
ffmpeg -i input.mp4 -r 15 -s 176x144 -b:v 96k -acodec libopencore_amrnb -ac 1 -ar 8000 -ab 12.2k output.3gp