Is it ok to copy/paste blog post from other sources?
I keep seen a lot of blog posts from third-party sources and is most likely the alleged authors are committing plagiarism and violating copyright from copying text, pictures as well as other medias.
One note is to warn those people to avoid copying text as well as media without it's owner approval, avoid DMCA and further law suit.
Stop flooding the web with repeated content, be creative and create your own content.
I suggest people to look for licenses such as Creative Commons and other type of licenses where the author explicitly allow you to re-use the media thereby providing link back or crediting the author.
Places to find such work:
Wikimedia Commons
RaumRot
Pixabay
IsoRepublic
There are many other sources, make sure you have authorisation to use the media before you publish, fair use does not necessarily means free and if you are not careful you might have a lot of headache ahead.
It is Ok for you to post videos and blogs ect.. from other sources as long as you give credit to the author where you got it from. To do that, you just need to post a link to their youtube video or their original article.
But original content is preferred.
Not necessarily, Roni Loren has shared her experience and I believe people can learn from it http://www.blogher.com/bloggers-beware-you-can-get-sued-using-photos-your-blog-my-story