While listening to what people interviewed were saying, I couldn't help feeling a bit sad in a nostalgic way.

nostalgic 是由希腊词根 nostos（"回家"）和 algos（"痛苦"）组成的形容词，字面意思是"思乡的痛苦"。现在用来形容"对过去美好时光的怀念之情"，即"怀旧的"。