请帮我解释一下这几个英语句子.1.She said that memorizing the words of pop s

请帮我解释一下这几个英语句子.
1.She said that memorizing the words of pop songs also helped a little.（她说记流行歌曲的歌词也会有点帮助）为什么memorize用ing形式?还有为什么用helped?
2.He finds watching movies frustrating becase the people speak too quickly.(他发现看电影使人沮丧因为人们说话太快了.）为什么在movies frustrating 中间不用加was或者is?我觉得没有be动词不顺口啊,但这些都是书上的原句.