Thanks for the replies, all of which were helpful.
Here is the upshot. I followed Rich Melville's advice, shut down and rebooted my Samsung Galaxy Note 8 smartphone. Now, I am able to attach a photo, and a video, to Forum posts, so that problem may be solved. However,ò it still took a long time, about 3 minutes, to upload the photo, and about 5 minutes to upload the video. The video was only 10 seconds long.
In the past, it took a few seconds to upload a short video, and virtually no time to upload a photo. It might take a minute, not more to upload a 50 second video onto a Forum post.
Anyone know the cause of my current uploading delay of attached photos and videos?
I don't know if the prolonged uploading time is caused by the Forum or my smartphone. I have about 3,000 photos/videos in the Gallery of my smartphone.
Arnold