Tvheadend

Try quoting your variables: instead of -i $zsite, try -i "${zsite}".

Also, you can simplify your ffmpeg command:
ffmpeg -i "${zsite}" -c copy -f mpegts pipe:1

The -c option applies to all streams, and the -tune zerolatency option is for encoding with libx264, which is not being used if you are merely passing the stream.

I tried that, and I am getting the same errors.

I also tried using changing my script to the specific link from youtube-dl, indicating to me the script is not the problem, but the way I am referencing the file in TV_Headend.

Is my reference to the script as "file:///home/tv/Documents/NASA_TV.sh" correct...?

Below is my script:

#!/bin/bash

pipe:///usr/bin/ffmpeg -i https://manifest.googlevideo.com/api/manifest/hls_playlist/id/Fih5Wpe6ac4.4/itag/95/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/cmbypass/yes/goi/160/sgoap/gir%3Dyes%3Bitag%3D140/sgovp/gir%3Dyes%3Bitag%3D136/hls_chunk_host/r1---sn-a8au-j8be.googlevideo.com/ei/0bAHWcTxCNSUuwLG1LTwAQ/playlist_type/DVR/gcr/us/mm/32/mn/sn-a8au-j8be/ms/lv/mv/u/pl/21/dover/6/upn/ihAh3lEsSL0/mt/1493676011/ip/66.234.180.86/ipbits/0/expire/1493697840/sparams/ip,ipbits,expire,id,itag,source,requiressl,ratebypass,live,cmbypass,goi,sgoap,sgovp,hls_chunk_host,ei,playlist_type,gcr,mm,mn,ms,mv,pl/signature/7A1BE89C6D20523C44F2DC75A65508C0B72EE8C4.3F25509954178C0655B2668306AF8BBA7DA6641E/key/dg_yt0/playlist/index.m3u8 -c copy -f mpegts pipe:1

And I entered "file:///home/tv/Documents/NASA_TV.sh" as the URL.

I tried livestreamer and now I get a signal, but it appears to start at the beginning of the stream about 1 year ago with no audio. I used:
pipe:///usr/bin/livestreamer https://www.youtube.com/watch?v=Fih5Wpe6ac4 720p --stdout

While adjusting the resolution, I once got the 'live' feed, but no audio. After adjusting the resolution to one of the others, and changed it back to 720p, I start at the beginning.

The log entry for using the 'best' option is below (This time gave me the live feed without audio):

2017-05-08 15:31:32.227 mpegts: NASA TV in Test IP - tuning on IPTV
2017-05-08 15:31:32.228 subscription: 0031: "172.20.5.153 [ TvLand | Kodi Media Center ]" subscribing on channel "Nasa_TV", weight: 150, adapter: "IPTV", network: "Test IP", mux: "NASA TV", provider: "FFmpeg", service: "Service01", profile="htsp", hostname="172.20.5.153", username="172.20.5.153", client="Kodi Media Center"
2017-05-08 15:31:32.230 spawn: Executing "/usr/bin/livestreamer"
2017-05-08 15:31:32.521 spawn: [cli][info] Found matching plugin youtube for URL https://www.youtube.com/watch?v=Fih5Wpe6ac4
2017-05-08 15:31:32.830 spawn: [cli][info] Available streams: 144p (worst), 240p, 360p, 480p, 720p (best)
2017-05-08 15:31:32.830 spawn: [cli][info] Opening stream: 720p (hls)
2017-05-08 15:31:33.729 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = -18000, last = 429360
2017-05-08 15:31:33.729 tsfix: transport stream H264, DTS discontinuity. DTS = -18000, last = 432000
2017-05-08 15:31:34.000 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = -18000, last = 431280
2017-05-08 15:31:34.000 tsfix: transport stream H264, DTS discontinuity. DTS = -18000, last = 432000
2017-05-08 15:31:38.653 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = -18000, last = 429360
2017-05-08 15:31:38.654 tsfix: transport stream H264, DTS discontinuity. DTS = -18000, last = 432000
2017-05-08 15:31:42.180 subscription: 0031: "172.20.5.153 [ TvLand | Kodi Media Center ]" unsubscribing from "Nasa_TV", hostname="172.20.5.153", username="172.20.5.153", client="Kodi Media Center"
2017-05-08 15:37:46.436 mpegts: NASA TV in Test IP - tuning on IPTV
2017-05-08 15:37:46.439 subscription: 0032: "172.20.5.153 [ TvLand | Kodi Media Center ]" subscribing on channel "Nasa_TV", weight: 150, adapter: "IPTV", network: "Test IP", mux: "NASA TV", provider: "FFmpeg", service: "Service01", profile="htsp", hostname="172.20.5.153", username="172.20.5.153", client="Kodi Media Center"
2017-05-08 15:37:46.441 spawn: Executing "/usr/bin/livestreamer"
2017-05-08 15:37:46.762 spawn: [cli][info] Found matching plugin youtube for URL https://www.youtube.com/watch?v=Fih5Wpe6ac4
2017-05-08 15:37:47.072 spawn: [cli][info] Available streams: 144p (worst), 240p, 360p, 480p, 720p (best)
2017-05-08 15:37:47.072 spawn: [cli][info] Opening stream: 720p (hls)
2017-05-08 15:37:48.105 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = 0, last = 449280
2017-05-08 15:37:48.106 tsfix: transport stream H264, DTS discontinuity. DTS = 0, last = 450000
2017-05-08 15:37:48.373 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = 0, last = 447360
2017-05-08 15:37:48.373 tsfix: transport stream H264, DTS discontinuity. DTS = 0, last = 450000
2017-05-08 15:37:53.314 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = 0, last = 449280
2017-05-08 15:37:53.315 tsfix: transport stream H264, DTS discontinuity. DTS = 0, last = 450000
2017-05-08 15:37:58.664 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = 0, last = 447360
2017-05-08 15:37:58.664 tsfix: transport stream H264, DTS discontinuity. DTS = 0, last = 450000
2017-05-08 15:38:03.838 tsfix: transport stream AAC-LATM, DTS discontinuity. DTS = 0, last = 445440

Any suggestions..?

Thanks.

Figured it out. The URL I was using loops videos and contains no audio. I used a different link, and I get audio and video.